from: http://blogs.msmvps.com/systmprog/2006/10/30/dns-and-active-directory-best-practices/

1. DNS is pointing to itself in TCP/IP property.

2. You have configured Forwarders tab in DNS Server property to access Internet.

3. You have checked the box “Register this connection in DNS” in TCP/IP property.

4. SOA RR entry is pointing to the same DNS Server address. Expand Forward Lookup Zone > domain_name.com and then in Right Pane find the SOA and NS records and make sure they are configured to use this DNS Server’s IP Address.

5. If you have *two NICs* make sure DNS is only *listening* on the LAN Interface.

6. Issue Ipconfig /registerdns command in Domain controller.

and more

From: http://www.dslreports.com/forum/r24566434-DNS-Best-DNS-Servers-To-Use-With-Comcast-

DNS Benchmark: https://www.grc.com/dns/benchmark.htm

GRCs DNS Benchmark performs a detailed analysis and comparison of the operational performance 
and reliability of any set of up to 200 DNS nameservers (sometimes also called resolvers) at once

From: http://code.google.com/p/namebench/

It hunts down the fastest DNS servers available for your computer to use. namebench runs a 
fair and thorough benchmark using your web browser history, tcpdump output, or standardized
datasets in order to provide an individualized recommendation.
namebench is completely free and does not modify your 
system in any way. This project began as a 20% project at Google.