domain lookups - briefing

Sometimes you can learn something useful by looking up who owns a domain and where they are located.  For example, if somebody posts on a newsgroup and leaves their email address, you may be able to determine their country by the domain.  If they are posting from a small ISP, you may even be able to determine their city!  Another interesting use of domain lookups is to find unknown domains owned by companies from known domains (i.e. find out how many different ways a key word like lucent (from Lucent Technologies) appears in domain names).  This is useful to track down back door sites not intended for public consumption -  these can be the best targets of all!