Am 27.01.2022 um 06:59 schrieb Tim via users users@lists.fedoraproject.org:
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- DHCP can accept a hostname from a client, but it doesn't have to.
- DHCP can give a hostname to a client, but it doesn't have to, and
the client doesn't have to accept it.
- A host can find out its hostname from its IP address. I recall
having to specify how many dots to count to separate hostname from domain name (e.g. if you were fred.bargle.flargle.net.au, your domain name could bargle.flargle.net.au or flargle.net.au, and therefore there were two possibilities of what your hostname might be).
A particular advantage of having the host and domain names being worked out from polling your DNS server is that the details will be consistent with what everything else thinks you are.
A particular disadvantage is that a reverse lookup does not have to be unambiguous. On the contrary, it is very common that several hosts share one IP. So, in many cases it will provide you with a list of hostnames. Which one to choose?
A DHCP provided hostname is unambiguous (or empty).
For the Apache example: If Apache finds a unique hostname, it will be used. A warning is issued if inconsistencies occur (e.g. between hostname and DNS check). No problem for Apache, in case of doubt the request is delivered to the default server. A valid solution.