[skarnet]

Except it's... not quite correct. getent performs NSS resolution, not DNS resolution, so its output depends on the value of the hosts field in your /etc/nsswitch.conf, which could be set to something fun like LDAP or something else.

I don't know Kubernetes, so it's very possible that Kubernetes enforces that name resolution is always DNS and only DNS (a "hosts: dns" line in /etc/nsswitch.conf, without any additional stuff like files which would mean resolution via /etc/hosts), in which case getent is indeed correct, but in the general case, there is no system-intrinsic tool that tests DNS only, and you have to use something like dig.