#networking

16 networking interview questions, asked at Amazon, Databricks, Google and 8 more companies. Last asked Sep 2026.

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IPv4 range iterator with reverse and CIDR supportCodingAn IPv4 address such as "172.16.4.9" is four octets, each 0 to 255. Taken together, the octets form one unsigned 32-bit number. Build iterators that walk IPv4 addresses lazily…
Last asked Sep 2026
Ordered IP firewall with CIDR rulesCodingImplement an IPv4 firewall that checks addresses against an ordered list of rules. Each rule is a pair (action, target). action is "ALLOW" or "DENY". target is either a single…
Last asked Sep 2026
Design a content delivery networkSystem designDesign a CDN that serves static content from servers close to users. Cover how a request reaches the nearest edge, what the edge caches and for how long, cache misses and the path…
Last asked Sep 2026
Convert a hexadecimal address to dotted IPv4CodingGiven a 32-bit address written in hexadecimal, return it in dotted-decimal IPv4 form, for example C0A80001 becomes 192.168.0.1. Decide and state how you treat an optional 0x…
Last asked Aug 2026
Explain how TLS secures a connectionCodingA networking fundamentals question after a coding exercise: explain how TLS sets up a secure connection between a client and a server, and how it protects the data afterwards…
Last asked Aug 2026
Stepwise DNS resolver with aliasingCodingBuild a simplified DNS resolver step by step against a fixed test harness: basic name lookup first, then alias layers on top. Later steps assume the earlier ones work. - Level 1:…
Last asked May 2026
Design a highly available load balancerSystem designDesign a load balancer that stays up when its own machines fail: how traffic is spread across backends, how unhealthy backends are detected, and how the load balancer itself…
Last asked May 2026
Parallel chunked download with integrity checkCodingChange a sequential chunked file download to fetch chunks in parallel, then verify the reassembled file's integrity. Reported on 1point3acres' Baseten bank; reconstructed in our…
Last asked Feb 2026
Host several websites on one server with one public IPSystem designYou have one server and one public IP address, and three small businesses each want their own website at their own domain. Explain how to serve all three from that machine, then…
Last asked Feb 2026
Infrastructure fundamentals: networking, Kubernetes and streamingSystem designA rapid-fire round of around twenty short questions with no coding, for an infrastructure role. Reported ones: 1. What happens between typing a site's address in the browser and…
Last asked Jan 2026
IP range to CIDR blocksCodingGiven a starting IPv4 address and a count n, return the shortest list of CIDR blocks that covers exactly the n consecutive addresses starting there, and no address outside that…
Last asked Jan 2026
Cloud infrastructure: VPC layout, IP planning and central managementSystem designA support-engineering screen of cloud infrastructure questions: how would you lay out a VPC with several tiers? With 2,000 servers, how many IP addresses and what CIDR blocks do…
Last asked Sep 2025
Troubleshoot high CPU, slow responses and DNS failuresCodingA production service shows high CPU, rising latency, and some requests failing on name resolution. Explain step by step how you investigate each: the tools and commands you would…
Last asked Sep 2025
Read whole messages from a socket streamCodingWrite a reader that returns complete messages from a socket, where each read may return part of a message or several messages at once. Define the framing (for example a length…
Last asked Sep 2025
IP routing table with longest prefix matchCodingBuild the forwarding table of an IPv4 router. Routes are CIDR prefixes mapped to a next-hop name. When a packet arrives, the router must send it to the next hop of the most…
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Design a VM bandwidth rate limiterSystem designCap the network bandwidth each virtual machine in a cloud region may use, enforcing per-tenant limits across many hosts without adding latency to packets.