Cisco Interview

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Cisco Interview Process: Complete 2026 Guide

Interviewed at Cisco in 2021 for a network software engineer role. Got the offer but went with a different company. The process was thorough but not overwhelming – here’s what to expect.

Overview

Cisco is networking infrastructure at massive scale. They invented much of the internet as we know it. The interview reflects their focus: strong fundamentals, systems thinking, and real-world problem-solving over algorithmic tricks.

Don’t expect leetcode hard questions. Expect deep technical discussions about networks, protocols, and building reliable systems.

Interview Structure

Phone Screen (45 minutes):

  • 1 coding problem (medium difficulty)
  • Discussion of networking concepts
  • Questions about your background
  • Why Cisco?

My phone screen: Implement a simple routing algorithm, then discuss TCP vs UDP tradeoffs.

Onsite (4-5 hours, can be virtual):

  • 2 coding rounds (45 min each)
  • 1 system design round (60 min)
  • 1 networking deep dive (45 min)
  • 1 behavioral round (30 min)

Technical Focus Areas

1. Networking Knowledge (Critical)

This is Cisco – they WILL test networking:

  • OSI model (all 7 layers)
  • TCP/IP protocols
  • Routing algorithms (OSPF, BGP)
  • Network security
  • Load balancing
  • DNS, CDN concepts

Know your networking fundamentals cold.

2. Data Structures & Algorithms (Moderate)

Medium leetcode level:

  • Graphs (very important for routing)
  • Trees (prefix trees for routing tables)
  • Hash tables
  • Queues (for packet processing)
  • Some string manipulation

Focus on graph algorithms – shortest path, traversal, etc.

3. System Design (Network Focus)

Expect network-related design questions:

  • Design a load balancer
  • Design a CDN
  • Design a distributed firewall
  • Design a monitoring system for network devices

4. C/C++/Python Skills

Cisco uses low-level languages for performance:

  • C/C++ for systems programming
  • Python for automation and tooling
  • Understanding of memory management
  • Performance optimization

Coding Interview Tips

Round 1 – Algorithms:

Problem I got: “Given a network topology as a graph, find the shortest path between two routers considering link costs.”

This is Dijkstra’s algorithm. They wanted:

  • Working implementation
  • Handling of edge cases (disconnected nodes, negative weights)
  • Time/space complexity analysis
  • Discussion of when to use Dijkstra vs Bellman-Ford

Round 2 – Implementation:

Problem: “Implement a rate limiter for network traffic.”

Required:

  • Token bucket or leaky bucket algorithm
  • Thread safety considerations
  • Performance optimization
  • Testing approach

System Design Interview

Question: “Design a globally distributed CDN.”

Cover:

  1. Architecture: Edge servers, origin servers, routing
  2. Caching: What to cache, eviction policies
  3. Routing: How to route users to nearest edge
  4. Consistency: Cache invalidation strategies
  5. Monitoring: Health checks, metrics

They care about practical details – “How do you handle a datacenter outage? How do you update cached content?”

Networking Deep Dive

This round was unique to Cisco. Expect detailed technical questions:

  • “Explain how TCP congestion control works.”
  • “What happens when you type a URL in a browser?” (network perspective)
  • “How does BGP routing work?”
  • “Explain the difference between L2 and L3 switching.”
  • “How would you troubleshoot packet loss?”

Be ready to go deep. If you say you know something, they’ll test you on it.

Behavioral Interview

Cisco values:

  • Collaboration: Working across teams
  • Innovation: New approaches to problems
  • Customer focus: Enterprise customers matter
  • Integrity: Doing the right thing

Questions:

  • “Tell me about a time you debugged a complex systems issue.”
  • “How do you handle disagreements with team members?”
  • “Describe a project where you had to learn new technology.”

Preparation Strategy

Networking (2-3 weeks):

  • Review OSI model thoroughly
  • Understand TCP/IP stack
  • Study routing protocols
  • Practice explaining concepts simply

Coding (3-4 weeks):

  • 50-75 leetcode medium problems
  • Focus heavily on graphs
  • Practice in C++ or Python
  • Emphasize clean, efficient code

System Design (2 weeks):

  • Study CDN architectures
  • Learn about load balancers
  • Understand distributed systems basics
  • Focus on reliability and scale

Difficulty: 6.5/10

Easier than FAANG (7-9/10) but requires strong networking knowledge that many software engineers lack.

If you have a strong networking background, it’s manageable. If you’re pure software with weak networking, prepare thoroughly.

Compensation (2024 data)

  • New grad: $110-130K base + $15-30K stock
  • Mid-level: $130-160K base + $30-60K stock
  • Senior: $160-220K base + $60-120K stock
  • Staff+: $220-300K+ total comp

Lower than FAANG but very good work-life balance. Bonus is 10-15% of base.

Culture & Work-Life Balance

Pros:

  • Excellent work-life balance (40 hours/week)
  • Stable, mature company
  • Working on critical infrastructure
  • Good benefits and perks
  • Remote options available

Cons:

  • Slower pace than startups
  • Some bureaucracy
  • Less exciting tech for pure software folks
  • Compensation below FAANG

My Experience

Coding rounds went well – I had practiced graph algorithms specifically for Cisco. Networking deep dive was tough but I had studied. Got the offer but went with a higher-paying opportunity.

If I had taken it, would’ve been a solid choice for someone who wants work-life balance and enjoys networking.

Final Tips

  1. Study networking deeply: This is non-negotiable
  2. Practice graph algorithms: Come up frequently
  3. Think about scale and reliability: Network infrastructure must always work
  4. Show passion for networking: They want people who care about packets
  5. Ask about the product: Cisco has many divisions – know which one

Cisco is great if you want to work on fundamental internet infrastructure with good work-life balance. Not flashy, but solid and stable.

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