Originally posted by: tony.evans
ServerX's hostname
is ServerX.
This is entirely independent of your network and DNS configuration.
However, it's usual for a server to be able to resolve its own hostname into an IP address, and it usually does this by using its own hosts file. Even if a server uses DNS, it's useful to have an entry in /etc/hosts for the hostname and IP address combination.
On top of that, it's also useful for other hosts to be able to resolve your server name to an IP address and that's where DNS comes in, so yes, there probably should be an entry in your DNS setup to resolve ServerX to a valid hostname, and you may want to remove ServerA and then set it up as an alias (CNAME) against the actual hostname.
There is no 'fault' here, it's just wrongly configured for whatever reason.
i.e. ServerA (label) in DNS resolve to an IP address that you've got assigned to ServerX (hostname) and ServerX doesn't have an entry in its own host file or is being forced to use DNS only.
It's pretty crucial for a healthy distributed server environment, to understand the basics of TCP/IP, addressing and DNS, and to make sure all your systems are in synch.
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