Why does it appear that some .CO domain names are not able to be registered?
In some limited cases, domains that might appear as available in WHOIS might not actually be available as they could be already registered and the WHOIS not yet updated and/or they could be part of the .CO Internet Restricted Domains list. In these cases, performing a check through your registrar or reseller provider's domain name search will give you the actual status of the domain. Additionally, domains currently or previously used as extensions in 3rd level domains will not be available for registration in the 2nd level. For example, org.co, mil.co, edu.co, com.co, net.co, nom.co, arts.co, firm.co, info.co, int.co, web.co, rec.co and co.co.