What should you focus on for a Network Engineer interview?
What makes these interviews different?
Routing, switching, firewalls and VPNs stand out. Network administration appeared more often in these interviews than across all interviews. Network security and telecom systems also appeared more often. Mid-level questions were the largest group, followed by junior and senior questions.
Start by checking whether you can explain route selection, firewall policies and VPNs. Then move beyond definitions: can you describe how you would investigate a network problem? The questions cover both how networks work and how you manage them.
How well do you know routing and switching?
BGP appeared in 21 of 64 interviews. Explaining BGP and describing how it prevents routing loops were among the most repeated questions.
Can you answer these clearly?
- How does BGP prevent routing loops?
- Which BGP attributes can influence outbound traffic?
- When are OSPF LSA Types 3, 5 and 7 used?
- How does administrative distance affect route selection?
- What are VLANs and trunks used for?
- What problems do spanning tree and link aggregation address?
The switching questions also cover switch stacking, Nexus vPC and Cisco ACI. Can you explain what each is used for?
Can you explain the basics and security topics?
The OSI model was another frequently repeated question. Can you explain what each layer does, rather than only name it? Also check whether you can explain static versus dynamic IP addresses, single-mode versus multimode fiber, and CRC versus checksum.
Firewall, VPN and network security questions appeared in 26 of 64 interviews. Can you explain firewall policies, NAT, TLS certificates and IPsec? For authentication and remote access, can you describe what you would check when access does not work?
Can you talk through network operations?
Network design and troubleshooting questions appeared in 30 of 64 interviews. Can you describe how you would use monitoring and packet analysis during an incident? Can you explain how capacity and QoS affect a network design?
The questions also cover upgrades, change control and documentation. Can you describe how you would plan a network upgrade, handle change control and document the changes?
Do you need to write code?
There were no code-writing tasks in these interviews. Automation still appeared as a topic, alongside systems administration. Can you explain how Python, Ansible or Terraform can support network work? Can you describe how you would handle configuration backups and synchronization?
What Network Engineer interviews cover
The 20 most asked Network Engineer questions
Counted by interview, not by mention: a question asked twice in one conversation counts once.
What is the OSI model, and what does each layer do?
Asked in 4 of 64 interviews · last asked Sep 29 · Concept · Junior
Show answer
The OSI model is a seven-layer framework for describing network communication. Physical sends bits; Data Link handles frames and local delivery; Network routes packets between networks. Transport provides end-to-end delivery; Session manages communication sessions. Presentation handles data formats, encryption, and compression; Application provides network services to applications.
- From layer one to seven: Physical, Data Link, Network, Transport, Session, Presentation, Application.
- Transport reliability depends on the protocol: TCP provides reliable delivery; UDP does not guarantee delivery.
- OSI is a reference model; real protocols do not always fit neatly into one layer.
- Layers help narrow troubleshooting to issues such as cables, addressing, routing, or application services.
What the interviewer checks: The interviewer checks whether you know each layer’s role and can separate different types of network problems.
Other ways it was asked
- “What is the OSI model?”
- “What are the layers of the OSI model?”
- “What does each layer of the OSI model do?”
How does BGP prevent routing loops?
Asked in 4 of 64 interviews · last asked Sep 29 · Concept · Mid-level
Show answer
By default, BGP rejects routes whose AS_PATH contains its own AS number. Inside an AS, iBGP does not advertise routes learned from one iBGP peer to another. Route reflectors are an exception; they use ORIGINATOR_ID and CLUSTER_LIST to prevent loops. When redistributing between OSPF and BGP, I use tags and filters to prevent route feedback.
- AS_PATH checking prevents loops between autonomous systems, but does not detect loops within one AS.
- Standard iBGP needs a full mesh; route reflectors reduce the required peer connections.
- Route reflectors reject routes when ORIGINATOR_ID matches their router ID or CLUSTER_LIST contains their cluster ID.
- Redistribution policies must stop routes from returning to their source routing protocol.
What the interviewer checks: The interviewer checks whether you understand loop prevention between ASes, inside iBGP, and during redistribution.
Other ways it was asked
- “How does iBGP prevent routing loops, apart from checking the AS path?”
- “What mechanism does BGP use to prevent routing loops?”
- “How would you prevent routing loops in a network running OSPF and BGP?”
Can you explain BGP?
Asked in 4 of 64 interviews · last asked Aug 19 · Concept · Junior
Show answer
BGP, or Border Gateway Protocol, is a path-vector routing protocol that exchanges routes between autonomous systems, such as ISP networks. It chooses routes using routing policies and path attributes, not just the shortest path. I would use it for routing between networks, especially when connecting to multiple ISPs.
- eBGP exchanges routes between autonomous systems; iBGP shares BGP routes within one autonomous system.
- BGP uses TCP port 179 to establish sessions between peers.
- The AS_PATH attribute lists autonomous systems along a route and helps prevent routing loops.
- Attributes such as local preference and AS_PATH influence route selection.
What the interviewer checks: The interviewer is checking whether you understand BGP’s purpose, basic operation, and common uses.
Other ways it was asked
- “What is BGP, and when would you use it?”
- “How does BGP work?”
- “What is BGP?”
What are the OSPF LSA types, including Types 3, 5, and 7, and when is each used?
Asked in 3 of 64 interviews · last asked Apr 24 · Concept · Mid-level
Show answer
In OSPFv2, Types 1 and 2 describe routers and shared networks within an area. Type 3 advertises networks between areas, while Type 4 shows how to reach an ASBR in another area. Type 5 carries external routes, except into stub areas and NSSAs. Type 7 carries external routes inside an NSSA.
- Every router creates Type 1; a designated router creates Type 2 when it has fully adjacent neighbors.
- Area border routers (ABRs) create Types 3 and 4.
- Autonomous system boundary routers (ASBRs) create Type 5, or Type 7 inside an NSSA, for redistributed routes.
- An NSSA ABR translates eligible Type 7 LSAs into Type 5 LSAs for use outside the NSSA.
What the interviewer checks: The interviewer checks whether you understand LSA purposes, which routers create them, and where they can travel.
Other ways it was asked
- “What are the OSPF LSA types, and when is each used?”
- “What is the difference between OSPF LSA types?”
- “What is the difference between OSPF LSA Type 3 and Type 5?”
Which BGP attributes can you use to influence outbound traffic routing?
Asked in 3 of 64 interviews · last asked May 26 · Concept · Mid-level
Show answer
I use LOCAL_PREF to choose the preferred outbound exit across my AS, or Cisco weight on one router. Higher values are preferred for both. Weight is not advertised to other routers. For inbound traffic, I can use AS_PATH prepending, MED, or provider-supported communities, but the remote network controls its choice.
- LOCAL_PREF is shared within the AS and takes priority over AS_PATH length.
- Cisco weight affects only the local router and takes priority over LOCAL_PREF.
- Shorter AS_PATHs are preferred when higher-priority attributes tie.
- Lower MED is preferred, but by default it is compared only between routes from the same neighboring AS.
What the interviewer checks: The interviewer is checking whether you distinguish local exit control from attempts to influence remote routing decisions.
Other ways it was asked
- “Which BGP attributes can you use to influence inbound traffic routing?”
- “Which BGP attributes can you use to manipulate route selection?”
- “What BGP options can you use to influence route selection for inbound versus outbound traffic?”
What is the administrative distance of external BGP (eBGP)?
Asked in 3 of 64 interviews · last asked Apr 24 · Concept · Junior
Show answer
On Cisco routers, the default administrative distance of eBGP is 20. A lower administrative distance is preferred when different routing sources offer routes to the same network prefix.
- eBGP: default administrative distance is 20 on Cisco routers.
- iBGP: default administrative distance is 200 on Cisco routers.
- External EIGRP: default administrative distance is 170 on Cisco routers.
- Defaults vary by vendor, and administrative distance can be changed.
What the interviewer checks: The interviewer checks whether you know default route preferences and can distinguish external and internal routing sources.
Other ways it was asked
- “What is the administrative distance of internal BGP (iBGP)?”
- “What is the administrative distance of eBGP?”
- “What is the administrative distance for external EIGRP?”
What is the difference between a dynamic IP address and a static IP address?
Asked in 2 of 64 interviews · last asked Aug 12 · Concept · Junior
Show answer
A dynamic IP address is assigned automatically, usually by DHCP, and can change over time. A static IP address is configured to stay the same until someone changes it. Dynamic addresses reduce setup work, while static addresses are useful for devices that need a predictable address, such as servers.
- A dynamic address can stay the same across DHCP lease renewals.
- Static addresses need careful management to avoid address conflicts.
- A DHCP reservation can give a device a consistent address while keeping automatic configuration.
What the interviewer checks: The interviewer is checking whether you understand address assignment, stability, and when to use each type.
Other ways it was asked
- “What is the difference between a static and a dynamic IP address?”
Can you explain the difference between single-mode and multimode fiber?
Asked in 2 of 64 interviews · last asked Apr 7 · Concept · Junior
Show answer
Single-mode fiber carries one light mode, while multimode fiber carries many. Single-mode supports longer distances because it avoids signal spreading caused by different modes arriving at different times. Multimode is common for shorter links within buildings or data centers, where its optics often cost less.
- Single-mode has a smaller core, typically about 9 micrometers; multimode cores are usually 50 or 62.5 micrometers.
- Maximum distance depends on link speed, fiber type, and the optical modules used.
- Match the fiber type and optical modules at both ends.
What the interviewer checks: The interviewer is checking whether you can choose suitable fiber and optics for a link’s distance, speed, and budget.
Other ways it was asked
- “What are the differences between multimode and single-mode fiber?”
- “What is the difference between single-mode and multimode fiber?”
What is the difference between CRC and checksum?
Asked in 2 of 64 interviews · last asked Mar 28 · Concept · Junior
Show answer
CRC uses polynomial division on bits to calculate an error-checking value. A simple checksum usually adds data words together. CRC generally detects burst errors more reliably than a simple checksum. Both detect data corruption, but neither repairs the damaged data.
- CRC is technically a type of checksum, but interviews usually compare it with simple additive checksums.
- Ethernet uses CRC; IPv4 headers, TCP, and UDP use additive checksums.
- Neither provides reliable protection against intentional changes by an attacker.
What the interviewer checks: The interviewer checks whether you understand how these error checks work and where networks use them.
What are the various types of ARQ protocols?
Asked in 2 of 64 interviews · last asked Mar 28 · Concept · Junior
Show answer
The main Automatic Repeat reQuest (ARQ) protocols are Stop-and-Wait, Go-Back-N, and Selective Repeat. Stop-and-Wait sends one frame and waits for an acknowledgment. Go-Back-N allows multiple frames in flight but retransmits the missing frame and all later unacknowledged frames. Selective Repeat retransmits only missing or damaged frames.
- ARQ uses acknowledgments and retransmissions to recover from transmission errors or loss.
- Stop-and-Wait is simple but wastes capacity when round-trip delay is high.
- Go-Back-N and Selective Repeat use sliding windows to keep multiple frames in flight.
- Selective Repeat needs more receiver buffering and tracking but avoids unnecessary retransmissions.
What the interviewer checks: The interviewer is checking whether you understand how each ARQ protocol handles lost frames and balances efficiency against complexity.
What is TCP?
Asked in 2 of 64 interviews · last asked Mar 28 · Concept · Junior
Show answer
TCP stands for Transmission Control Protocol. It is a connection-based transport protocol that delivers a reliable, ordered stream of bytes between applications. It uses acknowledgments and retransmissions to recover missing data, and controls how fast data is sent.
- TCP usually establishes a connection with a three-way handshake.
- It uses port numbers to identify application endpoints.
- Flow control protects the receiver; congestion control reduces pressure on the network.
- TCP provides a byte stream, not separate messages, and does not provide encryption.
What the interviewer checks: The interviewer is checking whether you understand TCP’s role and how it provides reliable communication.
Other ways it was asked
- “What does TCP mean?”
- “What is the TCP protocol?”
What are the functions of the data link layer?
Asked in 2 of 64 interviews · last asked Mar 28 · Concept · Junior
Show answer
The data link layer transfers frames between devices on the same link. It handles framing, link-layer addressing, and access to shared media. It also detects transmission errors; some data link protocols provide error recovery and flow control.
- Framing organizes network-layer packets into units sent over a link.
- Ethernet uses MAC addresses, which switches use to forward frames.
- Media access rules control when devices can transmit on a shared medium.
- Error detection does not guarantee recovery; Ethernet does not retransmit corrupted frames at this layer.
What the interviewer checks: The interviewer is checking whether you understand local frame delivery and can separate it from IP routing.
What are network and broadcast addresses in an IPv4 subnet, and what purpose does each serve?
Asked in 2 of 64 interviews · last asked May 7 · Concept · Junior
Show answer
The network address identifies an IPv4 subnet; all its host bits are zero. The broadcast address is used to send traffic to all hosts on that subnet; all its host bits are one. In a normal broadcast-capable subnet, neither address can be assigned to a host.
- The subnet mask determines which bits identify the network and which identify hosts.
- Routing tables use network addresses and prefix lengths to describe destination subnets.
- A /31 point-to-point subnet uses both addresses as hosts; a /32 identifies one address. Neither has a broadcast.
CodeSubnet: 192.168.1.0/24 Network: 192.168.1.0 Broadcast: 192.168.1.255 Host range: 192.168.1.1–192.168.1.254What the interviewer checks: The interviewer checks whether you can distinguish a subnet identifier, a broadcast destination, and usable host addresses.
Other ways it was asked
- “What is a broadcast address in IPv4 subnetting?”
What do you know about spanning tree—what is it for, and why is it important?
Asked in 2 of 64 interviews · last asked Apr 27 · Concept · Junior
Show answer
Spanning Tree Protocol (STP) prevents Layer 2 loops when switches have redundant connections. It keeps some paths blocked so frames cannot circulate endlessly, causing broadcast storms and unstable MAC address tables. If an active link fails, it can activate a backup path, allowing redundancy without loops.
- Switches elect a root bridge and choose loop-free paths toward it.
- Redundant paths are blocked from forwarding normal traffic, not physically disconnected.
- The topology is recalculated when links or switches fail.
- Rapid Spanning Tree Protocol (RSTP) usually recovers faster than classic STP.
What the interviewer checks: The interviewer is checking whether you understand Layer 2 loops and how spanning tree makes redundant switching safe.
Other ways it was asked
- “Tell me about spanning tree and why it is important.”
What are the OSPF external route types E1 and E2, and what is the difference between them?
Asked in 2 of 64 interviews · last asked Apr 24 · Concept · Mid-level
Show answer
E1 and E2 are OSPF route types for routes imported from outside OSPF. E1 adds the internal OSPF cost to the external metric. E2 compares the external metric first and uses internal cost to break ties. E2 is the usual default for redistributed routes.
- For the same destination prefix, OSPF prefers E1 over E2, regardless of their metric values.
- E1 accounts for the cost of reaching the external exit, which helps when several exits exist.
- E2 favors the lowest external metric, even if reaching that exit costs more internally.
What the interviewer checks: The interviewer is checking whether you understand external route metrics, route preference, and the default redistribution type.
Other ways it was asked
- “What is the difference between OSPF external route types E1 and E2, and which one is the default?”
If you redistribute routes between BGP and OSPF, how would you prevent routing loops, such as routes learned from OSPF being sent back into OSPF through BGP?
Asked in 2 of 64 interviews · last asked Jun 11 · Scenario · Senior
Show answer
I use route maps to mark redistributed routes and block them from returning to their source protocol. For OSPF routes entering BGP, I set a BGP community and reject that community when redistributing back into OSPF. For BGP routes entering OSPF, I use an OSPF route tag and block that tag on the return path.
- Apply the same loop-prevention policy at every redistribution router.
- OSPF tags do not automatically become BGP communities; configure the marking explicitly.
- Ensure BGP communities are preserved and sent between relevant peers.
- Use prefix filters to redistribute only the routes each protocol needs.
What the interviewer checks: The interviewer checks whether you can track route origin and prevent feedback across multiple redistribution points.
Other ways it was asked
- “When redistributing routes, how do you prevent routing loops?”
- “How can route maps be used to prevent routing loops during route redistribution?”
If a router has the same /24 route learned through OSPF and BGP, which route is preferred?
Asked in 2 of 64 interviews · last asked Mar 6 · Concept · Mid-level
Show answer
It depends on whether the BGP route is external or internal, and on the router’s route preference settings. With Cisco’s default administrative distances, eBGP beats OSPF, but OSPF beats iBGP. The values are eBGP 20, OSPF 110, and iBGP 200; lower wins.
- For the same prefix, administrative distance decides between routing protocols, not their metrics.
- With all three routes available, eBGP wins under Cisco defaults.
- Other vendors may use different defaults, and configured preferences can change the result.
What the interviewer checks: The interviewer is checking whether you distinguish eBGP from iBGP and understand administrative distance.
Other ways it was asked
- “If a router has three equal routes to 10.0.0.0/24—one learned through eBGP, one through OSPF, and one through iBGP—which route will it prefer?”
What is OSPF?
Asked in 2 of 64 interviews · last asked Sep 17 · Concept · Junior
Show answer
OSPF (Open Shortest Path First) is a link-state routing protocol used within an autonomous system. Routers share link information and use Dijkstra’s algorithm to find the lowest-cost paths. It supports areas to reduce routing overhead in larger networks.
- Path cost is the sum of link costs, which are commonly based on interface bandwidth.
- In multi-area OSPF, other areas connect to the backbone, Area 0.
- It supports equal-cost multipath routing, allowing traffic to use multiple paths.
- It is an open standard supported by many network equipment vendors.
What the interviewer checks: The interviewer is checking whether you understand how OSPF selects routes and scales using areas.
Other ways it was asked
- “What is OSPF, and what are its defining characteristics?”
What is the administrative distance of OSPF?
Asked in 2 of 64 interviews · last asked Mar 6 · Concept · Junior
Show answer
OSPF has a default administrative distance of 110 on Cisco routers. Other vendors may use different values. Administrative distance helps a router choose between routes to the same network learned from different sources.
- Lower administrative distance is preferred for routes to the same network prefix.
- Administrative distance is different from OSPF cost, which selects paths within OSPF.
- The default administrative distance can be changed.
What the interviewer checks: The interviewer is checking whether you know OSPF’s default value and how administrative distance affects route selection.
How do static and dynamic routing differ, and why would you choose dynamic routing at scale?
Asked in 2 of 64 interviews · last asked Apr 13 · Concept · Junior
Show answer
Static routes are set manually, while dynamic routing uses protocols to learn routes and update them when the network changes. At scale, I choose dynamic routing because it reduces manual work and can find another path after a failure. Static routes still suit small, stable networks and simple default routes.
- Protocols such as OSPF and BGP exchange route information and select paths using metrics or policy.
- Static routing becomes harder to maintain as routers, paths, and network changes increase.
- Dynamic routing needs time to converge after changes; failover requires an available alternative path.
- Dynamic routing adds CPU, memory, and control traffic overhead, plus configuration complexity.
What the interviewer checks: The interviewer checks whether you can balance routing simplicity, scale, and recovery after failures.
Other ways it was asked
- “Would you prefer static or dynamic routing?”
- “From a design perspective, what problems does static routing create, and why would you choose dynamic routing instead at scale?”
- “How does dynamic routing work, and when would you use it?”
Networking fundamentals interview questions
Fundamentals questions cover OSI layers, Ethernet, TCP and UDP, IP addressing, subnetting, DNS, DHCP, cabling, fiber optics and packet flow. 84 questions.
When would you choose TCP over UDP, or UDP over TCP, for an application, and what must the application handle in either case?
Asked once · last asked Feb 3 · Concept · Mid-level
Other ways it was asked
- “When would you choose TCP over UDP, or UDP over TCP?”
How would you troubleshoot a down fiber connection between two routers in the same room, where the connection runs from an optic to a patch panel, through structured fiber to another patch panel, and then to the other router?
Asked once · last asked Feb 3 · Scenario · Mid-level
How would you troubleshoot a machine connected to a switch port with an assigned VLAN that does not get an IP address dynamically, but works and communicates when configured with a static IP?
Asked once · last asked Feb 3 · Scenario · Mid-level
Why does TCP behave differently from UDP?
Asked once · last asked Feb 3 · Concept · Junior
How could you connect a copper-only switch to a fiber network?
Asked once · last asked Feb 3 · Scenario · Mid-level
What happens when you type `ping www.google.com` into a terminal on your computer?
Asked once · last asked Feb 3 · Concept · Junior
What is the TCP three-way handshake, and which packets would you expect to see when troubleshooting a connectivity problem?
Asked once · last asked Mar 6 · Concept · Mid-level
In a Wireshark capture, what does a TCP window-zero notification mean?
Asked once · last asked Mar 20 · Concept · Mid-level
What does the window size mean in a TCP packet?
Asked once · last asked Mar 20 · Concept · Junior
Which device sets the window size on a TCP connection?
Asked once · last asked Mar 20 · Concept · Junior
What are the various fields in the Ethernet frame format?
Asked once · last asked Mar 28 · Concept · Junior
What IP address conflicts can occur if an old switch remains connected, and how would you diagnose them?
Asked once · last asked Apr 7 · Scenario · Mid-level
Network switching and data center interview questions
Switching questions cover VLANs, trunks, VTP, spanning tree, link aggregation, switch stacking, Nexus vPC, Cisco ACI and Fibre Channel. 60 questions.
What is the difference between a VLAN and a subnet?
Asked once · last asked Feb 3 · Concept · Mid-level
What is the difference between a tagged and an untagged VLAN port?
Asked once · last asked Feb 3 · Concept · Mid-level
What is VXLAN, and when would you use it?
Asked once · last asked Feb 19 · Concept · Mid-level
What is a major difference between pairing two Nexus switches and stacking Catalyst 3850 switches, and what underlying technology accounts for that difference?
Asked once · last asked Mar 6 · Concept · Mid-level
What does the vPC peer-switch command do on Cisco Nexus switches?
Asked once · last asked Mar 6 · Concept · Mid-level
What command do you configure under a port channel to add it to a vPC?
Asked once · last asked Mar 6 · Tooling · Mid-level
What is an orphan port in a Nexus VPC implementation?
Asked once · last asked Mar 6 · Concept · Mid-level
What does it mean to have a root bridge and a secondary root, and how would you configure them?
Asked once · last asked Mar 6 · Tooling · Mid-level
What mechanisms can you use to prevent spanning-tree loops?
Asked once · last asked Mar 6 · Concept · Mid-level
What is storm control, and when would you use it on a network switch?
Asked once · last asked Mar 6 · Concept · Mid-level
Why do we create VLANs, and what is their purpose for separating different groups?
Asked once · last asked Mar 6 · Concept · Junior
If a port channel has two 10-gigabit links carrying a traffic session, what is the maximum bandwidth that session can use?
Asked once · last asked Mar 6 · Scenario · Mid-level
Other ways it was asked
- “Why might a single traffic session on a port channel with two 10-gigabit links be limited to one link's bandwidth?”
Show 7 more
How would you manage an MDS switch in a Fibre Channel environment?
Asked once · last asked Mar 19 · Tooling · Mid-level
What steps do you take when building and configuring network switches?
Asked once · last asked Mar 20 · Tooling · Mid-level
When configuring Arista switches through CloudVision Portal, how do you generally apply the configuration?
Asked once · last asked Mar 20 · Tooling · Mid-level
What does it mean to collapse or simplify the layers in a switching network?
Asked once · last asked Mar 23 · Concept · Mid-level
How would you design VLANs for CCTV and a corporate network in the same environment?
Asked once · last asked Apr 6 · Design · Mid-level
What is the main difference between a traditional data center model and ACI?
Asked once · last asked Apr 7 · Concept · Mid-level
How would you configure VLAN 1030 on a switch?
Asked once · last asked Apr 8 · Scenario · Junior
Routing and OSPF interview questions
Explore static and dynamic routing, administrative distance, route selection, OSPF areas and LSAs, redistribution and routing loops. 44 questions.
How does your strongest routing protocol work, and how would you troubleshoot it?
Asked once · last asked Mar 12 · Scenario · Mid-level
When might static routing be used with VXLAN instead of dynamic routing, and how would you evaluate whether it is the right design?
Asked once · last asked Feb 19 · Scenario · Senior
What common issues can occur with BGP and OSPF, and how would you troubleshoot them?
Asked once · last asked Feb 24 · Scenario · Mid-level
How do you perform route redistribution between BGP and OSPF?
Asked once · last asked Feb 24 · Tooling · Mid-level
Do all OSPF areas need to connect to area 0?
Asked once · last asked Feb 27 · Concept · Mid-level
How can you use the show ip route command to view OSPF routes?
Asked once · last asked Feb 27 · Tooling · Junior
With an OSPF E2 route, if there is one external route but multiple paths to reach it, is the internal cost used?
Asked once · last asked Feb 27 · Concept · Senior
What mechanisms can you configure to control which routes are advertised, or which metrics are injected, when redistributing between routing protocols?
Asked once · last asked Mar 6 · Tooling · Senior
If you have two OSPF links, one primary and one secondary, and the primary link is up but experiencing problems, how can you fail over traffic to the secondary without shutting down the interface?
Asked once · last asked Mar 6 · Scenario · Senior
What is an OSPF passive interface, and when would you use one?
Asked once · last asked Mar 6 · Concept · Mid-level
What configuration changes would you make to help BGP and OSPF detect link failures quickly?
Asked once · last asked Mar 11 · Scenario · Senior
What does the interface bandwidth command affect, including routing metrics and other features?
Asked once · last asked Mar 20 · Concept · Mid-level
Other ways it was asked
- “What are the implications of configuring the bandwidth command on an interface, and where can it be used?”
- “How does a routing protocol use the bandwidth value configured on an interface?”
- “Besides influencing routing-protocol metrics, what other effects can the interface bandwidth command have?”
Show 1 more
How would you make new routes propagate automatically without manually changing a route map, route filter, or access list each time?
Asked once · last asked Apr 7 · Scenario · Senior
BGP interview questions
BGP questions cover peering, path selection, routing policy, traffic engineering, ISP failover, route reflectors and missing-route troubleshooting. 53 questions.
What are BGP communities, and how are they used to influence routing policy?
Asked in 2 of 64 interviews · last asked Apr 7 · Concept · Mid-level
Other ways it was asked
- “What are BGP communities, and how are they used?”
How would you configure BGP to prefer a primary ISP and automatically fail over to a secondary ISP?
Asked in 2 of 64 interviews · last asked Apr 27 · Scenario · Mid-level
Other ways it was asked
- “You have an internet router in your data center with BGP configured to AT&T and Verizon. How would you configure BGP so traffic from inside your company prefers the AT&T circuit to reach the internet, using Verizon only as a backup?”
- “How would you configure BGP on an internet router to prefer the AT&T circuit for outbound traffic, with Verizon as a backup?”
- “How would you configure BGP so inbound internet traffic prefers the Verizon circuit and uses AT&T as a backup?”
Which BGP attributes would you use to prefer a primary link for inbound versus outbound traffic?
Asked in 2 of 64 interviews · last asked Aug 26 · Concept · Senior
Other ways it was asked
- “With BGP, how would you prefer a primary link over a secondary link, and which parameters would you use for incoming versus outgoing traffic?”
- “Which BGP technique affects inbound traffic versus outbound traffic?”
When would you use BGP over OSPF, and why?
Asked once · last asked Feb 3 · Scenario · Senior
Other ways it was asked
- “When would you use OSPF or BGP?”
Given a data center network to design, would you use iBGP or eBGP, and what are the reasons and benefits of your choice?
Asked once · last asked Apr 7 · Design · Senior
Other ways it was asked
- “For a data center network design, would you recommend iBGP or eBGP, and why?”
How would you use BGP to prioritize link A and design failover to link B within 200 milliseconds?
Asked once · last asked Sep 17 · Design · Senior
Other ways it was asked
- “How would you achieve failover from link A to link B within 200 milliseconds?”
What technology can detect a BGP neighbor failure within 200 milliseconds when the usual hold time is about 30 seconds?
Asked once · last asked Sep 17 · Concept · Senior
Other ways it was asked
- “What technology can detect a BGP neighbor failure within about 200 milliseconds without relying on the default hold time?”
What is the difference between MED and local preference?
Asked once · last asked Feb 24 · Concept · Mid-level
What does the BGP replace-as command do?
Asked once · last asked Feb 27 · Concept · Mid-level
What is the difference between the BGP local preference and weight attributes?
Asked once · last asked Feb 27 · Concept · Mid-level
How does local preference work?
Asked once · last asked Feb 27 · Concept · Mid-level
Can you walk me through the commands to establish a BGP adjacency between two directly connected switches in different autonomous systems?
Asked once · last asked Mar 6 · Tooling · Mid-level
Show 4 more
What command would you use to verify that the BGP adjacency has been established?
Asked once · last asked Mar 6 · Tooling · Junior
How would you check which routes you’re advertising from one switch to a BGP neighbor?
Asked once · last asked Mar 6 · Tooling · Mid-level
Why might an iBGP router fail to receive a route advertised by another router?
Asked once · last asked Mar 11 · Scenario · Mid-level
How would you achieve BGP route propagation without a route reflector?
Asked once · last asked Mar 11 · Concept · Mid-level
Firewall, VPN, and network security interview questions
Review questions about firewall platforms and policies, NAT, TLS certificates, IPsec, remote access, network access control, authentication and security troubleshooting. 66 questions.
What are the main VPN types, and how do their endpoints and use cases differ?
Asked in 2 of 64 interviews · last asked Apr 15 · Concept · Mid-level
Other ways it was asked
- “What are the main types of VPN, such as site-to-site and remote-access VPNs?”
- “What are the differences between client-to-client, client-to-firewall, and site-to-site VPNs?”
What is SIP ALG (also called SIP helper), and how can it affect SIP traffic over a VPN?
Asked once · last asked Feb 17 · Concept · Mid-level
How do you configure or troubleshoot DMVPN?
Asked once · last asked Feb 24 · Tooling · Mid-level
What is the difference between DMVPN Phase 2 and Phase 3?
Asked once · last asked Feb 24 · Concept · Mid-level
How would you troubleshoot ZPA or ZIA using the Zscaler console and user logs?
Asked once · last asked Feb 24 · Tooling · Mid-level
What are the main architectural differences between Cisco ASA and Palo Alto firewalls?
Asked once · last asked Feb 27 · Concept · Mid-level
Other ways it was asked
- “What are the differences between NAT policies on Cisco ASA and Palo Alto firewalls?”
For an Internet-facing FortiGate and a new FTP server in the DMZ that must be accessible from the Internet, what questions would you ask, and how would you approach the firewall configuration?
Asked once · last asked Mar 6 · Scenario · Senior
How would you fail over a Palo Alto firewall from active to passive? Walk me through the steps.
Asked once · last asked Mar 11 · Tooling · Mid-level
A user gets an SSL error when accessing a website through a Palo Alto firewall, but the site works on their phone. What might cause this, and how would you troubleshoot it?
Asked once · last asked Mar 11 · Scenario · Mid-level
How do you use Cisco ISE in network operations?
Asked once · last asked Mar 23 · Tooling · Mid-level
What difference do you see between Cisco ASA and Check Point?
Asked once · last asked Apr 6 · Concept · Mid-level
If we host websites internally for external users, what security checks would you make, and how would you design the traffic flow from our network to those users?
Asked once · last asked Apr 6 · Design · Senior
Show 8 more
How does public NAT work, and when would you use it?
Asked once · last asked Apr 6 · Concept · Mid-level
What is DMVPN, and when would you use it in a network?
Asked once · last asked Apr 7 · Concept · Mid-level
Can you explain the two phases of an IPsec tunnel?
Asked once · last asked Apr 7 · Concept · Mid-level
If an IPsec tunnel fails to establish or a previously working tunnel goes down, what would you check first, and what could cause the problem?
Asked once · last asked Apr 7 · Scenario · Mid-level
What are the five elements you configure for IPsec Phase 1?
Asked once · last asked Apr 7 · Concept · Mid-level
What steps or elements do you configure for IPsec Phase 2?
Asked once · last asked Apr 7 · Concept · Mid-level
Explain the different Palo Alto firewall deployment modes, including how virtual systems isolate traffic and how they relate to VLANs, NAT, and legacy firewalls.
Asked once · last asked Apr 13 · Concept · Mid-level
What is IPsec, and how is it used to secure network communications?
Asked once · last asked Apr 13 · Concept · Mid-level
Wireless and telecom interview questions
Wireless and telecom questions cover Wi-Fi design, authentication, RF surveys, cellular systems, voice gateways, roaming and product tradeoffs. 53 questions.
What is network slicing, and what purpose does it serve in a 5G network?
Asked once · last asked Oct 20 · Concept · Mid-level
Other ways it was asked
- “Why is network slicing important in 5G?”
If a call connects but has no audio for the first two seconds, even though signaling arrives on time, how would you troubleshoot the issue?
Asked once · last asked Feb 17 · Scenario · Mid-level
Other ways it was asked
- “What troubleshooting procedure would you use to investigate a call that has no audio for the first two seconds, and where would you check the logs?”
How would you set up a new ISDN or GSM gateway?
Asked once · last asked Feb 17 · Tooling · Mid-level
Other ways it was asked
- “How would you independently configure an ISDN or GSM gateway supplied by a reseller?”
If PRI lines stop working while the software shows them as operational and the hardware indicators are not blinking, how would you set up alerts to receive immediate notifications when you are away from the office?
Asked once · last asked Feb 17 · Scenario · Mid-level
If monitoring alerts fail, what daily checks would you perform to verify that PRI lines and gateways are operational?
Asked once · last asked Feb 17 · Scenario · Mid-level
An access point has been added to a Meraki wireless controller and shows a blue LED. What does that indicate, and how would you troubleshoot it and test connectivity from a phone?
Asked once · last asked Feb 24 · Scenario · Mid-level
How do you use RF tagging and troubleshoot access points on a Cisco 9800 controller?
Asked once · last asked Feb 24 · Tooling · Mid-level
Why wouldn’t you configure an access point to transmit at maximum power everywhere?
Asked once · last asked Mar 6 · Concept · Mid-level
Can you walk me through guest authentication, including where the captive portal is hosted and how a guest user is authenticated?
Asked once · last asked Apr 15 · Concept · Mid-level
Where do you configure the guest splash page in the wireless controller?
Asked once · last asked Apr 15 · Tooling · Mid-level
How does a corporate SSID user connect, and what authentication method and flow are used?
Asked once · last asked Apr 15 · Concept · Mid-level
Does EAP-TLS apply to domain-joined computers, and how do you provide wireless access for company-owned tablets or iPads that aren’t joined to the domain?
Asked once · last asked Apr 24 · Scenario · Mid-level
Show 8 more
What are Aruba AirWave, Aruba Central, Aruba Activate, and ClearPass used for in enterprise network management?
Asked once · last asked May 5 · Concept · Mid-level
What steps do you take for RF optimization?
Asked once · last asked Aug 6 · Scenario · Mid-level
Which KPIs do you use to monitor cellular network performance?
Asked once · last asked Aug 6 · Concept · Mid-level
Other ways it was asked
- “What issues do you look for when reviewing cellular network KPI trends?”
How would you troubleshoot high resource block (RB) utilization and low throughput in a cellular network?
Asked once · last asked Aug 6 · Scenario · Mid-level
Which KPI is commonly used to measure accessibility in a cellular network?
Asked once · last asked Aug 6 · Concept · Junior
How do you evaluate roaming vendors, manage technical onboarding, and identify areas for improvement?
Asked once · last asked Oct 19 · Scenario · Senior
What commercial or technical factors would justify adding other operators to a roaming solution?
Asked once · last asked Oct 19 · Case · Mid-level
How would you justify using a multi-MZ solution internally?
Asked once · last asked Oct 19 · Case · Senior
SD-WAN and cloud networking interview questions
Work through SD-WAN architecture, onboarding, OMP, WAN overlays, MPLS, hybrid connectivity and network design in AWS, Azure and Google Cloud. 24 questions.
How does the OMP protocol work in Cisco SD-WAN?
Asked in 2 of 64 interviews · last asked Apr 24 · Concept · Mid-level
Other ways it was asked
- “What is OMP in Cisco SD-WAN, and what role does it play?”
How would you connect an on-premises network to cloud resources in AWS or Azure?
Asked in 2 of 64 interviews · last asked Apr 7 · Scenario · Mid-level
Other ways it was asked
- “How would you connect resources in an Azure resource group to an on-premises site?”
- “What steps would you take to connect an on-premises router to AWS or Azure?”
Why might a secondary AWS Direct Connect link come up briefly and then go down?
Asked once · last asked Mar 11 · Scenario · Senior
Other ways it was asked
- “How would you troubleshoot and prevent a secondary AWS Direct Connect link from repeatedly coming up and going down?”
In a brief pitch, what benefits does SD-WAN offer compared with traditional routing?
Asked once · last asked Mar 6 · Concept · Mid-level
How would you design end-to-end connectivity between a VPC and an on-premises network using BGP?
Asked once · last asked Mar 11 · Design · Senior
What connectivity would you propose for five VNets that need low-latency, high-throughput connections to on-premises, with no encryption requirement?
Asked once · last asked Mar 11 · Design · Senior
Where would ExpressRoute terminate in Azure, and what configuration element would you need?
Asked once · last asked Mar 11 · Concept · Mid-level
What are the benefits of using a hub in Azure when connecting multiple VNets?
Asked once · last asked Mar 11 · Concept · Mid-level
What is ExpressRoute Global Reach, and what does it do?
Asked once · last asked Mar 11 · Concept · Mid-level
What are the main SD-WAN components, and what roles do vManage, vBond, and vSmart perform?
Asked once · last asked Apr 7 · Concept · Mid-level
Other ways it was asked
- “What are the main components of a Meraki or Viptela SD-WAN solution?”
- “What roles do vManage, vBond, and vSmart each perform?”
Which protocol does Cisco SD-WAN use to establish control connections between its controllers and WAN edge devices?
Asked once · last asked Apr 7 · Concept · Mid-level
How is IPsec used in an SD-WAN deployment?
Asked once · last asked Apr 13 · Concept · Mid-level
Show 8 more
What is the administrative distance of OMP?
Asked once · last asked Apr 15 · Concept · Mid-level
How would you onboard a new router into an SD-WAN fabric? Can you walk me through the steps?
Asked once · last asked Apr 15 · Scenario · Mid-level
How do you use a route reflector in SD-WAN?
Asked once · last asked Apr 15 · Concept · Senior
What is the administrative distance of OMP in Cisco SD-WAN?
Asked once · last asked Apr 24 · Concept · Mid-level
What is GRE (Generic Routing Encapsulation), and what are its advantages and limitations?
Asked once · last asked Jul 2 · Concept · Mid-level
What is MPLS (Multiprotocol Label Switching), and how does it work?
Asked once · last asked Jul 2 · Concept · Mid-level
How would you integrate Fortinet appliances into an SD-WAN network, and what connectivity considerations would you address?
Asked once · last asked Jul 16 · Design · Mid-level
How does SD-WAN handle path health versus the old OSPF cost approach?
Asked once · last asked Jul 17 · Concept · Mid-level
Network automation and systems administration interview questions
Automation and systems questions cover Python, Ansible, Terraform, configuration backups and synchronization, Windows, Linux, directory services, virtualization and storage. 37 questions.
What is the difference between a list and a tuple in Python?
Asked once · last asked Aug 19 · Concept · Junior
Other ways it was asked
- “What's the difference between a list and a tuple?”
How do you define a context manager in Python?
Asked once · last asked Aug 19 · Concept · Junior
Other ways it was asked
- “What is a context manager?”
How would you set up an Ansible environment and organize and manage playbooks?
Asked once · last asked Mar 11 · Tooling · Mid-level
How would you manage Ansible inventory, including how it is populated and how inventory changes are tracked?
Asked once · last asked Mar 11 · Tooling · Mid-level
How do RAID 5 and RAID 6 differ, and when would you use each?
Asked once · last asked Apr 6 · Concept · Mid-level
How would you automate firmware upgrades across multiple switches and firewalls?
Asked once · last asked Apr 6 · Scenario · Senior
How would you manage network integration between VMware ESXi hosts and vCenter?
Asked once · last asked Apr 13 · Scenario · Mid-level
Can you describe a PowerShell or Bash script or command-line task you would use for troubleshooting or basic automation?
Asked once · last asked May 1 · Tooling · Mid-level
Other ways it was asked
- “Do you have experience using PowerShell or Bash? Can you describe a script or command-line task you have used for troubleshooting or basic automation?”
Can you explain what Active Directory is and what kinds of objects you can manage in it?
Asked once · last asked May 12 · Concept · Junior
How would you set up a Windows file share, and what administration tasks can you perform in SharePoint or Microsoft 365?
Asked once · last asked May 12 · Tooling · Junior
How would you secure a Windows server against attacks?
Asked once · last asked May 12 · Scenario · Mid-level
How do you configure a Group Policy Object?
Asked once · last asked May 12 · Tooling · Mid-level
Show 8 more
How do you patch a Windows operating system?
Asked once · last asked May 12 · Tooling · Junior
How can you check network settings in Linux, and what command would you use?
Asked once · last asked May 12 · Tooling · Junior
How does virtualization work, and how would you deploy a virtual machine?
Asked once · last asked May 12 · Concept · Junior
How does a virtual machine get the resources it needs to run?
Asked once · last asked May 12 · Concept · Mid-level
How do you manage Active Directory accounts, configure two-factor authentication, and manage Google account settings?
Asked once · last asked Jul 16 · Tooling · Mid-level
How do you use automation in network management, and what value do templates and scripting provide when configuring switches, routers, and firewalls?
Asked once · last asked Jul 16 · Tooling · Mid-level
What is Terraform, and how can you use it to manage network changes such as changing a VLAN ID?
Asked once · last asked Sep 17 · Tooling · Mid-level
How would you back up network device configurations across vendors, including devices unsupported by your existing tool?
Asked once · last asked Sep 17 · Scenario · Senior
Other ways it was asked
- “How would you back up the running configurations of network devices and support devices from different vendors?”
- “How would you handle backing up Cisco device configurations when an existing tool does not support Cisco?”
Network design and troubleshooting interview questions
These questions cover network architecture, capacity, QoS, monitoring, packet analysis, incident response, upgrades, change control, documentation and project proposals. 61 questions.
How would you design a network for a doctor's office with up to 100 client devices, 10 servers, a secure remote connection to the hospital, and wireless guest access to the internet but not the intranet?
Asked once · last asked Feb 3 · Design · Senior
How would you estimate the required bandwidth and internet speed for an office with 30 agents making calls through a dialer and 15 other users browsing the internet, including VPN usage?
Asked once · last asked Feb 17 · Scenario · Mid-level
Using the existing documentation as a baseline, how would you validate the infrastructure and understand the environment well enough to contribute?
Asked once · last asked Feb 19 · Scenario · Mid-level
Suppose you have two data centers experiencing latency issues and both routers use BGP. How would you start troubleshooting?
Asked once · last asked Feb 24 · Scenario · Senior
How do you perform upgrades on F5 load balancers?
Asked once · last asked Feb 24 · Tooling · Mid-level
When planning a network consolidation, how do you define the target environment and identify the source networks or systems?
Asked once · last asked Mar 6 · Scenario · Mid-level
What is the difference between upgrading a network switch and upgrading its NX-OS software?
Asked once · last asked Mar 6 · Concept · Mid-level
If someone reports an issue with a machine and gives you its IP address, how would you troubleshoot and verify the issue, including which device you would log in to and what you would check?
Asked once · last asked Mar 6 · Scenario · Mid-level
How do you determine whether network changes should be made during a maintenance window or regular business hours?
Asked once · last asked Mar 20 · Scenario · Mid-level
How would you troubleshoot a report that a user is experiencing slow network connectivity? What would your thought process be?
Asked once · last asked Mar 20 · Scenario · Mid-level
If you found that bandwidth between access and core was an issue, what would you do, and how would you determine that was the cause?
Asked once · last asked Mar 23 · Scenario · Mid-level
What circumstances, if any, justify making a network change without formal change control?
Asked once · last asked Mar 23 · Scenario · Mid-level
Show 8 more
How would you implement QoS for video traffic?
Asked once · last asked Apr 6 · Scenario · Mid-level
As a network design engineer, how would you design a network to be efficient and support future expansion?
Asked once · last asked Apr 7 · Design · Senior
When installing a router in a data center, what process do you follow to determine the rack elevation and spacing, choose the correct vendor-provided SFP, and complete the installation?
Asked once · last asked Apr 7 · Scenario · Mid-level
What is quality of service (QoS), and when would you use it on a network?
Asked once · last asked Apr 13 · Concept · Mid-level
How would you upgrade a switch using Cisco DNA Center?
Asked once · last asked Apr 15 · Tooling · Mid-level
Tell me about a time you handled a significant network event. What happened, what steps did you take, and what tools or applications did you use to identify and resolve the problem?
Asked once · last asked Apr 23 · Behavioral · Mid-level
How would you design a highly available network for a building if money were no issue?
Asked once · last asked Apr 27 · Design · Senior
How would you safely upgrade a pair of redundant building core switches from the 4500 chassis series to the 9500 series?
Asked once · last asked Apr 27 · Scenario · Senior
Other ways it was asked
- “How would you prepare for a migration from redundant 4500-series core switches to 9500-series switches?”
Related interview questions
- Computer Networks interview questions
- System Design interview questions
- DevOps Engineer interview questions
- Cloud Engineer interview questions
- System Administrator interview questions
- IT Support and Help Desk interview questions
- Cybersecurity interview questions
How this list is made
Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.
Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.
The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every Network Engineer interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.
64 interviews, 34 candidates, Nov 2025 to Oct 2026. Updated every month with new interviews.
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