Actually, most Unices get their gethostbyname()-type functions from libc. Maybe Linux machines use libresolv a lot these days, though....

And nslookup doesn't actually use libresolv or the gethostbyname()-type functions. It does direct DNS queries, and absolutely never looks at a hosts file. It's intended solely as a DNS tool, not a more generic nameservice tool.

But whatever. I'm arguing semantics. I just wanted to make sure that a novice didn't make a stupid mistake.