How about implementing a new identifier called $naddr? $naddr would return the named address of a given ip (if one exists).

Ex:

//echo -a $naddr(209.240.130.48)

mIRC would return:

mirc.com

To get the "IP's name", mIRC has to perform a dns lookup. This is not instantaneous, so it can't be returned like an identifier. IF it would return instantneously, mIRC would have to hang until it recieve a result to pass to the identifier.

By the way, you can still use /dns 209.240.130.48
Then, get the results with on *:DNS:echo -a It's $raddress !

/help on dns for more info