Multiple domains pointed to the same IP

[Jeff Cochran]

>When you ftp, the server gets the IP address, 192.1.2.3.  It then does
>a gethostbyaddr(), to get the name from the PTR entry.  But since you
>could have a fake name in the PTR entry, it is necessary to verify
>that the name actually has that address.  To do this, it does a 
>gethotsbyname() using the PTR name, and checks through the addresses
>returned (there may be more than one) to see if any are the original address.
>(Sun does this inside gethostbyaddr(), otherwise it might be done by ftp).
>
>Now, if more than one name is returned by gethostbyaddr() should it look
>up all the names?  And then check all the addresses for those names?
>That seems unnecessary to me.  It is only necessary that one name have
>an A entry for that address.

So, basically, a confirmation for FTP purposes only requires that the
originating IP address have an A record host name that resolves to
that IP, not necessarily a host name matching the host name
originating the IP request, correct? 

In otherwords:

myhost.foo.com resolves to 10.0.0.10
10.0.0.10 resolves to myotherhost.bar.com
myotherhost.bar.com resolves to 10.0.0.10
IP verified, let the data flow!

Thanks for the help...

Jeff