DNS problem

[Steve Zatz]

I am not very familiar with DNS issues on either Linux or Windows but
I believe that is the problem that I am having.  If I type the IP
address of a site it loads quickly but if I type the name
(www.yahoo.com), it takes about 30 to 60 seconds to resolve the name. 
I have a Windows machine on the same home network that does not
exhibit this problem.  (I am connected to the Internet through a cable
modem.) When I originally installed Ubuntu, I didn't have this problem
but it has appeared over the last few days.  I do not think I made any
changes that might have introduced this problem but clearly something
has changed. If I type "host adress" an  ip address is generally
returned pretty quickly although intermittently "host www.yahoo.com"
returns "www.yahoo.com not found: 2(SERVFAIL)" which seems odd.  I am
running the release version of Warty on a Dell box.  Any thoughts or
pointers would be appreciated.