I just bought a new VPS hosting plan and i have a few questions.

Hope someone here can clear the doubts for me.

1) Is it necessary to have a real domain for a vps hostname? I suppose i can just use a non-real domain like anydomain.com and something like 'server' for the computer name.

Therefore i'll end up with something like server.anydomain.com as the vps's hostname.

I want to do this for the sake of putting in a hostname to configure the vps to get it going .

So, since this non-real domain name does not need to be publicly accessible i don't need to register or own it and instead access the server by the ip address. Is that correct?

But i suppose that this also depends upon if my web host allows that?

2)I would also like to run some real sites with real domain names on this vps, so can i just configure the zone file on the primary nameserver and make entries for these domains and point an A record at the Vps's IP to make them publicly accessible over the internet?

For example for my 1st domain i could make an entry like this:

$TTL 86400
mydomain1.com.          IN     SOA    ns1.mywebhost.com. \
                                admin.mydomain1.com. (
               2004011522     ; Serial no., based on date
                    21600     ; Refresh after 6 hours
                     3600     ; Retry after 1 hour
                   604800     ; Expire after 7 days
                     3600     ; Minimum TTL of 1 hour
                  )

server                IN     A       200._._._
ns1.mywebhost.com.      IN     A       216._._._
ns2.mywebhost.com.      IN     A       205._._._
@                     IN     NS      ns1.mywebhost.com.
@                     IN     NS     ns2.mywebhost.com.
@                     IN     MX      10 server
www                   IN     CNAME   server

server                IN     CNAME   @               (so this particular line tells the nameserver to point the url mydomain1.com to server.anydomain.com at the particular ip addresss in the A record.... is that right?)

Similarly for my 2nd domain i could have a similar entry :

$TTL 86400
mydomain2.com.          IN     SOA    ns1.mywebhost.com. \
                                admin.mydomain2.com. (.....

                   ............................so on........
                   .........................................
                   .........................................
                   .........................................
                   .........................................
                   .........................................

Is that correct?

3) Suppose for my vps hostname, i ignorantly chose a domain that someone else alreadys owns , however i think that it won't affect the public accessibility of the real domain or website since only the real owner of the domain has the rights to provide for the nameservers addresses in the TLD registeries through his Domian Registerar? Is that correct?

4)Can i change my vps's hostname later? Would this create any complications?