It's possible those addresses are no longer public open, which may be the case for any that are not actually designated public.
The two best known public DNSes, are:
OpenDNS - 208.67.222.222. 208.67.220.220
Google public DNS - 8.8.8.8 8.8.4.4
Another one is
http://www.dnsadvantage.com/
156.154.70.1
156.154.71.1
Name.space (alternate root)
209.48.2.11
209.48.2.189