DNS lookup fails but nslookup works

Actually it is probably due to using a .local domain. That conflicts with the mDNS resolution (zero configuration networking) which by default uses .local.

Some versions of OS X can support both name resolution methods, mDNS and normal DNS, but at least Yosemite doesn't seem to support it any more.

This little bit older Apple Support document explains the background. For Yosemite what does work still is adding "domain.local" to the DNS search list in the network settings.

The real solution is not using the .local domain for DNS resolved hosts.

For some, check /etc/resolver/ directory and delete any files there.

It seems as if this is due to me pointing to both internal and external dns servers on my client, as mentioned here. After I removed all external DNS servers from my list of servers, everything works as it should.