Ping fails but nslookup works

When performing nslookup, the IP can be returned. But when performing ping, return following error

ping: cannot resolve <hostname>: Unknown host

Causes

Second DNS server issue

The second DNS server isn't resolving the IP address.

Another DHCP server issue

Another DHCP server provide different DNS server.

Fix

killall -HUP mDNSResponder

References

DNS lookup fails but nslookup works