I'm trying to get a hostname from an ip address:

host <ipaddress>

but it doesn't give me the hostname. I tried nslookup and dig too but don't get the information I want.

in a nutshell I want the opposite of the host command used with a hostname to get the ip address,

It sounds like the reverse-lookup is not working correctly or not configured. Is this a local DNS server that you control or a public DNS server? If public, they may not offer/support reverse-lookups, or they can be very generic.

For instance, if you do a you get multiple IP addresses; one of which is 74.125.225.46.

If you do a it responds with: ord08s06-in-f14.1e100.net

That isn't a fault in the command. It's just that the IP doesn't have a PTR record set up.

You can read about PTR records and such here: http://help.dnsmadeeasy.com/spry_menu/ptr-record/

Additionally, sites on the internet at large might not support this, because they don't have PTR records, and because they are utilizing virtualhosts, and DNS does not support querying this way.

More information here on that: http://superuser.com/questions/33938...nting-to-an-ip

If you want to get fancy and get access to the entire TLD zone files, that you can turn into a database and query as you wish, you can visit here: http://www.verisigninc.com/en_US/cha...on/index.xhtml. This might not be what you are looking for as it probably contains nameserver info rather than ip mappings, but worth a mention.

that's exactly what I was trying to do. I was using the first address returned from:
host google.com

and then tried to get "google.com" to show up when I used:

host <google'sipaddress>

I've tried this on a few addresses but none of them give the actual hostname

Right. No reverse-dns set up.

It's particularly useful on Windows Domains to turn IP's into Hostnames. But the internet, not so much.