[regularjack]

Are you sure about that? ac, ai and tm do not resolve:

  nslookup tm
  Non-existent domain

Browsers are able to reach them by forwarding to ac.com, ai.com or tm.com

[hazov]

It does have an A record:

  % dig a tm
  
  ; <<>> DiG 9.7.3 <<>> a tm.
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41011
  ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
  
  ;; QUESTION SECTION:
  ;tm.				IN	A
  
  ;; ANSWER SECTION:
  tm.			86366	IN	A	193.223.78.213
  
  ;; Query time: 1 msec
  ;; SERVER: 192.168.66.32#53(192.168.66.32)
  ;; WHEN: Thu Jan 12 10:20:15 2012
  ;; MSG SIZE  rcvd: 36

And also an open http server:

  % nmap tm.
  Starting Nmap 5.00 ( http://nmap.org ) at 2012-01-12 10:24 BRST
  Interesting ports on serv213.icb.co.uk (193.223.78.213):
  Not shown: 997 filtered ports
  PORT    STATE  SERVICE
  80/tcp  open   http
  113/tcp closed auth
  443/tcp open   https

[icebraining]

You might want to check your DNS server, because nslookup tm works fine here.

And yes, browsers redirect to .com if you jut put "tm", but at least Firefox loads the correct website if you put the whole URL, with http://

[derefr]

    Server:	8.8.8.8
    Address:	8.8.8.8#53

    Non-authoritative answer:
    Name: tm
    Address: 193.223.78.213

Seems to be working for me.