odd DNS problem, maybe OT

[rikona]

I have an odd problem. I have lost the ability to connect to anything
from sat.wrh.noaa.gov or star.nesdis.noaa.gov - these give sat and
radar weather info. I can connect to
http://www.wrh.noaa.gov/satellite/?wfo=slc but when I try to go to
some specific map, say
http://sat.wrh.noaa.gov/satellite/showsat.php?wfo=slc&area=sw&type=ir&size=4
I get a 404 - sat.wrh.noaa.gov could not be resolved. I can't ping it
and whois says no address for it. I have two 10.04 boxes and both do
the same thing. It happens with both Opera and FF.

I wrote to the noaa webmaster, since some less-used sites are
sometimes down for a day or two, but he says they are running OK and
were/are not down.

I can go to essentially any other address/site on the net, but not to
these. I rebooted one of the UB boxes, and the router, and the problem
is still there. I did not reboot the Comcast cable modem [that's
another hassle on its own... for some reason it can take hours to get
it running again, with multiple calls to Comcast "support"].

I'd like to understand why this happens for just a couple of
addresses, and fix it - any suggestions would be much appreciated.
  
Thanks,

 rikona