Can anyone explain this error to me?

[Simon Waters]

Simon Guest wrote:
> 
> Attempts at looking up the in-addr.arpa PTR records of the name server
> ns2.perfectinternet.net via the address(es) 213.171.194.21 failed with the
> error(s): Name Error.

Not the clearest error message in history.

The reverse lookup of the name from the IP address returns "no
such name".

 dig -x 213.171.194.21

DNS turns names to numbers, and can turn numbers back to names,
but no one set up the number to name side for this server.

The delegation of this appears to be with RIPE still, but they
will be happy to help anyone set up reverse delegation, although
it may take them a while to respond. 

In the first place speak to whoever gave you your IP address.