Interview Preparation
25 CCNA Interview Questions & Answers
These are the networking interview questions freshers are asked most often, with concise, correct answers. Master the concepts behind them — don't just memorise — and you'll handle follow-ups confidently.
Fundamentals
- OSI vs TCP/IP? OSI has 7 layers (conceptual); TCP/IP has 4 (practical). Both describe how data moves across a network.
- Difference between a hub, switch and router? A hub repeats to all ports (Layer 1), a switch forwards by MAC address within a LAN (Layer 2), a router forwards between networks by IP (Layer 3).
- What is a collision domain vs broadcast domain? A switch port is its own collision domain; a VLAN/router interface bounds a broadcast domain.
- What is subnetting? Dividing an IP network into smaller subnets to use addresses efficiently and control broadcast size.
Switching
- What is a VLAN? A logical Layer 2 segment that separates devices on the same switch. See our VLAN guide.
- Access vs trunk port? Access = one VLAN for end devices; trunk = many VLANs between switches via 802.1Q.
- What does STP do? Spanning Tree Protocol prevents Layer 2 loops by blocking redundant paths.
- What is EtherChannel? Bundling multiple physical links into one logical link for more bandwidth and redundancy.
Routing
- Static vs dynamic routing? Static is manually configured; dynamic protocols (OSPF, EIGRP, BGP) learn routes automatically.
- How does OSPF choose paths? Lowest cost (based on bandwidth) using the SPF algorithm. See OSPF explained.
- What is administrative distance? A trust value for route sources — lower is preferred (e.g., OSPF 110, EIGRP 90).
- Default route? 0.0.0.0/0 — used when no specific route matches.
IP services & security
- What is NAT? Network Address Translation maps private IPs to public IPs so internal hosts can reach the internet.
- DHCP? Automatically assigns IP addresses and settings to hosts.
- What is an ACL? An Access Control List that permits or denies traffic based on rules.
- Port security? Restricts which MAC addresses can use a switch port, limiting unauthorised devices.
- TCP vs UDP? TCP is connection-oriented and reliable; UDP is connectionless and faster.
Pro tip
Interviewers value candidates who can explain and demonstrate. Practise these on real Cisco gear in our CCNA training with placement support.
Frequently asked questions
How should I prepare for a CCNA interview?
Revise core concepts (OSI, subnetting, VLANs, routing, NAT, ACLs), practise on real or simulated devices, and be able to explain not just 'what' but 'why'.
Do CCNA interviews include practical questions?
Often yes — expect scenario or configuration questions, so hands-on lab practice is essential.
Related articles
Want hands-on training?
Learn this on real Cisco lab devices with placement support at Attila Technologies, Ahmedabad.