Show MySQL host via SQL Command

Maybe

mysql> show processlist;

To get current host name :-

select @@hostname;
show variables where Variable_name like '%host%';

To get hosts for all incoming requests :-

select host from information_schema.processlist;

Based on your last comment,
I don't think you can resolve IP for the hostname using pure mysql function,
as it require a network lookup, which could be taking long time.

However, mysql document mention this :-

resolveip google.com.sg

docs :- http://dev.mysql.com/doc/refman/5.0/en/resolveip.html