Google·Software Engineer·Technical Phone Screen
- A Linux server's CPU usage suddenly spikes. Walk through your diagnostic process: which commands you'd run, how you'd isolate the offending processes or threads, and how you'd tell whether the bottleneck is user CPU, kernel CPU, or IO wait. What are your next steps once you've identified the cause?
- A service is showing high latency. How would you use tools like netstat, tcpdump, and traceroute or mtr to figure out whether the problem is on the client, the server, or somewhere in the network? What specific signals are you looking for, like SYN backlog, retransmits, RTT, or packet drops?
- Explain how DNS resolution works end to end, from stub resolver through recursive and authoritative servers, including caching and TTLs. Also, what's the practical difference between dig and nslookup, and when would you reach for one over the other?
“This one I actually felt decent about.”