Fast concurrent checking of SOA DNS records for .co.za domains

Question

I want to implement bulk availability checking of .co.za domain names as accurately as possible by checking for the existence of SOA

Answer 1

If the service offered on the Web "limits consecutive checks for a given IP", it is probably for good reasons (both to preserve the system and to make life more difficult for speculators). Calling it "archaic" certainly will not help.

Also, a lot of DNS requests may be seen as a violation of the terms of service and/or as a dictionary attack and may (disclaimer: I do not know the policies of co.za) lead to blacklisting.

Answer 2

This would be very easy using JH Software's DNS Client Library for .NET:

var Response = JHSoftware.DnsClient.Lookup("example.com", 
                              JHSoftware.DnsClient.RecordType.SOA);

It also supports BeginLookup / EndLookup methods for asynchronous lookups.