One of the in my spare time activities of life as a techie is providing network administration support to the family. Lately the in-laws have had some challenges getting online. When I asked them to visit http://whatismyip.com they would get different results each time. Their TiVo folks had said they had a problem with their IP address and that was why the TiVo wasn't working. Things got more interesting when I started looking up the ip addresses. The IP addresses reported belonged to companies on the other side of the globe. From Cambodia to Poland the information didn't make sense.
Interestingly although Remote Desktop wouldn't provide access (because of the bad IP address) screen sharing in iChat did work. Upon logging in and firing up AirPort Utility I expected to see that the AirPort knew it had a different address. But alas the AirPort resolutely stated the IP address in Poland.
So the thought goes through one's mind at this point... Is the cable company doing something to mask or block the IP information to prevent dynamic DNS and remote access? The idea seems far fetched but given some of the recent changes in various cable companies service it wouldn't be completely out of the question. The problem with this theory is figuring out how this would really be done on this sort of scale. A quick look over the blog-o-sphere reveals that there were no suggestions of this practice so it is pretty much ruled out.
The problem, it seems then, is in the cable modem. Something had gone haywire with the modem and it reported the wrong address even while the network was getting traffic routed relatively well. So after a quick trip to Radio Shack, and yes they do still exist, the problem was gone and a new cable modem was in place. Now to figure out where to get a broken cable modem repaired.