I want to stop apache2 from querying the dns name at every start and to make it faster. There is absolutely no reason for apache to do any DNS-queries at all. For redirects it has to use the name passed in by the client in the host header. (See http://httpd.apache.org/docs/2.2/mod/core.html#usecanonicalname )
This is for an embedded device btw and if I expose the hostname setting in the gui I better have a good reason to do so and can explain 100% what is affected by it!
So far I only see that the hostname is used by apache for nothing and it is but into the syslog.
I don't use http://httpd.apache.org/docs/2.2/mod/core.html#hostnamelookups or dns name based access rules. For more background about my problem, see http://httpd.apache.org/docs/2.2/dns-caveats.html . There it says:
To get this address it uses either the global ServerName (if present) or calls the C function gethostname (which should return the same as typing "hostname" at the command prompt). Then it performs a DNS lookup on this address. At present there is no way to avoid this lookup.