I’m sad to say that in above article you did not describe DNS at all. You instead described how to configure local name resolution on a Linux host through /etc/hosts. In this scenario, DNS is not involved at all.

Think of OS name resolution like an umbrella. In nsswitch.conf the sysadmin configures what name resolution services for this system should be. Files usually come first (means /etc/hosts), DNS is one of them – it usually follows files but there are a lot more different name resolution services and strategies available.

“getent hosts ” query the OS to resolve according to configured name resolution services in that order (and usually checks /etc/hosts firsts and then maybe DNS, but always does what’s written in nsswitch.conf behind “hosts:”)

“host” explicitly asks DNS service to resolve. This won’t resolve hostnames that only /etc/hosts can resolve – to demonstrate the difference.

Please read the man pages of “getent” and “hosts“.

I suggest completely overhaul this article or take it off-line.

Greetings,
Joerg