In this blog, you will find a comprehensive guide on “how to prepare for a networking interview”. Specifically tailored for individuals at the Network Role – Level 1, this resource offers a structured collection of Q&A to enhance your interview readiness. This quick guide organizes essential L1 networking questions into easy sections—perfect for last-minute revision. Use the table of contents to jump to any topic and skim crisp, interview-ready answers.
Table of Contents
- Networking Fundamentals
- Routing & Switching Basics
- IP Addressing & Subnetting
- Transport & Application Protocols
- Network Services
- Security & Architecture
- Wireless & Infrastructure
- Performance, QoS & Troubleshooting
Networking Fundamentals
1) What is the OSI model?
A 7-layer reference model for network communication: Physical, Data Link, Network, Transport, Session, Presentation, Application.
2) What is an IP address?
A unique logical identifier that enables devices to send/receive packets on a network.
3) What is a MAC address?
A hardware identifier burned into a network interface, used for Layer-2 forwarding on a LAN.
4) What is ARP?
Address Resolution Protocol maps IP addresses to MAC addresses on a local network.
5) Difference between unicast, multicast, and broadcast?
Unicast = one-to-one; Multicast = one-to-many (group); Broadcast = one-to-all in the broadcast domain.
6) What is a network topology?
The physical/logical arrangement of devices and links (e.g., star, bus, ring, mesh).
7) What is a network segment?
A portion of a network separated by a device (switch/router/bridge); often its own broadcast domain or IP subnet.
8) What is a loopback address?
127.0.0.1 (IPv4) and ::1 (IPv6) test the local host’s network stack.
9) What is a network hub?
A legacy device that repeats bits to all ports (half-duplex, no MAC learning), unlike a switch.
Routing & Switching Basics
10) What is the difference between a switch and a router?
A switch connects devices in a LAN and forwards frames by MAC (Layer 2). A router connects different networks and forwards packets by IP (Layer 3).
11) Difference between Layer 2 and Layer 3 switches?
L2 switch: MAC-based forwarding. L3 switch: can route between VLANs/subnets using IP (inter-VLAN routing).
12) What is a VLAN and why is it used?
Virtual LAN that splits one physical network into multiple broadcast domains for performance, security, and manageability.
13) What is a VLAN trunk?
A link carrying multiple VLANs between devices (e.g., switch-to-switch) using 802.1Q tagging.
14) What is a broadcast storm?
Excessive broadcast traffic that can degrade or halt a network; mitigated with proper design and loop prevention (e.g., STP).
15) What is a routing table?
The set of routes a router (or L3 switch) uses to decide where to forward IP packets.
16) What is a default gateway?
The router that forwards traffic from a local network to other networks.
17) What is static routing?
Manually configured routes that remain until edited; simple and predictable.
18) What is dynamic routing?
Routes learned/updated automatically via protocols like OSPF, EIGRP, or BGP.
IP Addressing & Subnetting
19) Difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses (~4.3B). IPv6 uses 128-bit addresses, vastly larger space, and features like SLAAC.
20) What is subnetting?
Dividing a larger network into smaller subnets to improve routing efficiency, performance, and address management.
Transport & Application Protocols
21) Difference between TCP and UDP?
TCP is connection-oriented and reliable (ordering/retransmission). UDP is connectionless, faster, and does not guarantee delivery or order.
22) Difference between HTTP and HTTPS?
HTTP is plaintext. HTTPS uses TLS for encryption and integrity.
Network Services
23) What is DHCP?
Automatically assigns IP configuration (IP, subnet mask, gateway, DNS) to clients.
24) What is a DHCP lease?
The time period for which an address is assigned before renewal is required.
25) What is DNS?
Resolves human-readable domain names to IP addresses.
26) What is NAT?
Network Address Translation rewrites private IPs to public (and back) so multiple devices can share a single public address.
27) What is port forwarding?
Mapping an external port on a gateway to a specific internal device/service.
28) What is SNMP?
Protocol for monitoring/managing network devices (agents, OIDs, traps/informs).
Security & Architecture
29) What is a firewall?
A security device/service that inspects and controls traffic based on rules (IPs, ports, protocols, applications).
30) What is a DMZ?
A semi-trusted network segment separating public-facing services from the internal LAN.
31) What is a VPN?
Creates an encrypted tunnel over an untrusted network (e.g., the internet).
32) What is an IPsec VPN?
A VPN built with the IPsec suite to authenticate and encrypt IP traffic.
33) What is a site-to-site VPN?
A VPN that securely connects entire networks (e.g., branch to HQ) over the internet.
34) What is a proxy server?
An intermediary between clients and the internet for caching, security, and policy control.
35) What is port security?
A switch feature restricting port access based on MAC addresses, with actions on violation.
Wireless & Infrastructure
36) What is an access point?
A device that connects wireless clients to a wired LAN.
37) What is a wireless controller?
A WLC centrally manages multiple APs (config, RF optimization, security).
38) What is PoE?
Power over Ethernet—carries data and electric power on the same cable (e.g., APs, IP cameras).
39) What is a patch panel?
A passive panel that organizes and terminates network cabling in racks.
40) What is load balancing?
Distributes traffic across servers/links to improve performance and availability.
Performance, QoS & Troubleshooting
41) What is bandwidth?
The maximum data transfer rate of a link.
42) What is latency?
The time delay between sending a request and receiving a response.
43) What is QoS?
Quality of Service mechanisms prioritize specific traffic (e.g., voice/video) to meet targets for latency, jitter, and loss.
44) What is ping used for?
Checks basic IP connectivity and measures round-trip time via ICMP echo.
45) What is traceroute used for?
Reveals the hop-by-hop path packets take to a destination for path/latency troubleshooting.
Closing note: Review these fundamentals with a lab mindset—test concepts (e.g., VLANs, NAT, ACLs) in a small sandbox or emulator and practice explaining them in 30–60 seconds. Clear structure + concise examples make strong interview answers.