Bot? check if a domain name is availible?
Solution 1:
On windows you can use
nslookup <domain name>
Example:
C:\>nslookup abc.com
Server: pd1nsc1.st.vc.XXXXX.net
Address: 64.59.144.XX
Non-authoritative answer:
Name: abc.com
Address: 199.181.132.250
Example no domain:
C:\>nslookup abceeeeeeeeeeeeeeeeeeeeee.com
Server: pd1nsc1.st.vc.XXXXX.net
Address: 64.59.144.XX
*** pd1nsc1.st.vc.shawcable.net can't find abceeeeeeeeeeeeeeeeeeeeee.com: Non-ex
istent domain
Every 3 letter domain has been registered on .com, .net, .org... I believe its the same with 4 letter domains, i think there is still some 5 letter domains left.
Solution 2:
Asking for all three-letter domains from the .com, .net, and .org servers should take about 17576 queries to each, so 52,728 total. Should take about 15 minutes to write the script, and a few minutes to run.
It won't get you exactly what you want, as not being in DNS does not exactly mean it is free. However, it's a good start.
Solution 3:
You should expect that all three-letter domains are taken and many are available for sale. Google is your friend (or perhaps not).