10 Cisco Software Engineer (New Grad) Interview Questions (2026)
Cisco's new-grad SWE loop in 2026 is a recruiter screen, an online assessment, and a three to four round virtual onsite covering coding, networking fundamentals, and behavioral. Many candidates apply through the CXC (Cisco Choose Your Career) program, which has its own bar; the regular-application loop is similar but with more emphasis on the specific team's tech stack (networking OS, security, collaboration tools).
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Loop overview
Recruiter screen → HackerRank OA (60-90 minutes, 2-3 problems) → 3-4 onsite rounds: typically two coding/technical, one networking/systems, and one behavioral. Some teams (e.g. ThousandEyes, Webex) replace the networking round with a domain-specific deep dive. Timeline is 4-6 weeks. Reports of long gaps between rounds are common.
Behavioral (3)
Tell me about a time you had to deliver a project under a tight deadline.
Frequently askedOutline
STAR: Situation (deadline, stakes, constraints) → Task (your specific deliverable) → Action (scope cuts, parallelization, who you pulled in) → Result (delivered, what you cut, what you learned). Avoid hero stories — show team coordination.
Why Cisco? Why not a pure software company?
Frequently askedOutline
Tie to a specific product or domain — security (Talos, Duo), networking OS, observability (ThousandEyes), or collaboration (Webex). Show you understand Cisco operates at the intersection of hardware and software. Avoid 'I like networking' alone.
Describe a time you had to debug an issue that no one else could figure out.
Occasionally askedOutline
Pick a concrete debugging story — preferably one with logs, traces, or a reproducible test case. Walk through your hypotheses, what you ruled out, and how you eventually found the root cause. End with the fix and what you put in place to prevent recurrence.
Coding (LeetCode patterns) (4)
Reverse a singly linked list, both iteratively and recursively.
Frequently askedOutline
Iterative: walk the list maintaining prev, curr, next pointers; flip curr.next = prev each step. O(n) time, O(1) space. Recursive: recurse to the tail, then set node.next.next = node and node.next = null. O(n) time, O(n) stack space. Be ready to discuss both.
Given an array of integers, find two numbers that sum to a target value.
Frequently askedOutline
Hash map of value → index, single pass. For each element, check if (target - element) is in the map; if so, return the pair. O(n) time, O(n) space. Mention the sorted-input two-pointer alternative for follow-up.
Given a binary tree, determine if it is a valid binary search tree.
Occasionally askedOutline
Recurse with a (min, max) range for each subtree. At each node, check value strictly between min and max. Recurse left with max=value, right with min=value. O(n) time, O(h) space. Common gotcha: do not just compare to immediate children.
Implement a function to detect a cycle in a linked list.
Occasionally askedOutline
Floyd's tortoise-and-hare: slow pointer moves 1 step, fast pointer moves 2 steps. If they meet, there is a cycle. O(n) time, O(1) space. Follow-up: find the start of the cycle (reset slow to head; move both 1 step until they meet again).
Technical (2)
Explain how the TCP three-way handshake works and what happens during connection teardown.
Frequently askedOutline
SYN, SYN-ACK, ACK. Walk through sequence numbers being established. Teardown is the FIN-ACK pair from each side (four packets total in the canonical case). Mention TIME_WAIT state and why it exists. This is bread-and-butter for any Cisco SWE role.
What is the difference between a router and a switch, at the protocol layer?
Frequently askedOutline
Switch operates at Layer 2 (MAC addresses, builds a CAM table, forwards frames within a broadcast domain). Router operates at Layer 3 (IP addresses, builds a routing table, forwards packets between networks). Mention modern L3 switches blur this line. Expect a follow-up on VLANs.
System / object-oriented design (1)
How would you design a simple URL shortener?
Occasionally askedOutline
For new-grad, keep it light: API (POST /shorten, GET /:code), storage (key-value: code → URL), code generation (base62 from auto-increment ID, or hash + collision check), and basic scaling (read-heavy, cache aggressively). Mention rate limiting and analytics as follow-ups.
Cisco interview tips
- Networking fundamentals matter at Cisco even for non-networking teams. Brush up on OSI layers, TCP/UDP differences, DNS, and HTTP. It signals you understand the business.
- The HackerRank OA is the main filter. Two medium problems in 60-90 minutes; do not spend more than 30 minutes on either before moving on.
- Cisco interviews can have long gaps between rounds (sometimes 2-3 weeks). Stay in touch with your recruiter without being pushy. Send a 'still interested' note after 10 days of silence.
- Be specific about which team you want. Cisco is huge — Webex, security, networking OS, ThousandEyes, and others are very different. Generic 'I want to work at Cisco' answers underperform.
- Behavioral rounds at Cisco lean conflict-and-collaboration. Have a story ready for: disagreement with a teammate, missed deadline, learning a new technology, and handling ambiguous requirements.
Frequently asked questions
How long is Cisco's SWE new-grad interview process in 2026?
Most reports show 4-6 weeks from application to offer. Reports of 8-10 week timelines are common when there are gaps between the OA and onsite. CXC (Cisco Choose Your Career) program candidates often have a faster turnaround.
Does Cisco ask system design for new-grad SWE interviews?
Generally not. New-grad onsite rounds focus on coding, data structures, and networking/systems fundamentals. A lightweight design question (URL shortener, simple key-value store) occasionally appears as a follow-up but is not a full round.
What programming language is best for Cisco interviews?
Python, Java, C, and C++ are all common. C and C++ are appreciated if you are interviewing for a networking OS or systems team. Otherwise, pick the language you are most comfortable with.
How does Cisco's CXC program differ from the regular new-grad application?
CXC (Cisco Choose Your Career) is Cisco's structured early-career program with rotational placements. The interview loop is similar but more focused on culture fit and long-term potential. Regular applications go directly to specific teams.
What is the offer timeline at Cisco after onsite?
Most candidates report 1-2 weeks from final round to offer. Team-match calls happen after the hiring decision and add 1 week. Compensation conversations happen after team match.
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