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
