This post is basic and aimed for IT managers and lab users.
In many cases the full domain is required to be added to the hostname when using SSH, otherwise the SSH/DNS will not be able to resolve/translate the name to IP address.
For example, in case I have a server called Server01 in a domain called mydomain.com, trying to ssh to the hostname only will not resolve.
# ssh admin@Server01
ssh: Server01: Name or service not known
To resolve this, create/edit a file called ~.ssh/config, under ~.ssh/ folder, and add the following lines to it.
Once doing that, the SSH will replace the host with the hostname plus the full domain.