Why it does not propogate ?

[Cricket Liu]

> As far as I know 'mail.ontero.com' is not registered. 

Then you're not looking very hard:

$ whois mail.ontero.com.
[whois.crsnic.net]

Whois Server Version 1.3

Domain names in the .com, .net, and .org domains can now be registered
with many different competing registrars. Go to http://www.internic.net
for detailed information.

   Server Name: MAIL.ONTERO.COM
   IP Address: 209.157.66.9
   Registrar: REGISTER.COM, INC.
   Whois Server: whois.register.com
   Referral URL: www.register.com

cricket