LFCS Question #268: Real Exam Question with Answer & Explanation

Question

Suppose that the command netstat -a hangs for a long time without producing output. An administrator might suspect:

Options

• Aa problem with NFS
• Ba problem with DNS
• Ca problem with NIS
• Da problem with routing
• Ethat the netstat daemon has crashed

Explanation

A hanging netstat -a command often indicates issues with DNS resolution, as the command attempts to resolve IP addresses to hostnames, which can delay output if DNS servers are unreachable or slow.

Common mistakes.

• A. A problem with NFS would typically manifest as issues accessing mounted file systems, not as a hang in netstat -a during connection listing.
• C. A problem with NIS (Network Information Service) would affect user/group lookups across the network, but generally not cause netstat -a to hang.
• D. Routing problems would prevent network connections, but netstat -a would still display local connections and listening ports, and wouldn't hang specifically on hostname resolution.
• E. netstat is a utility, not a daemon, and therefore does not 'crash' in the sense of a daemon process failing.

Concept tested. netstat troubleshooting and DNS

Reference. https://man7.org/linux/man-pages/man8/netstat.8.html

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