I came back to my apartment today after not being there for a couple of days, to find that our (my flatmate and I) router died due to a power outage. I needed internet access so I hooked up my laptop directly to the cable modem (a Motorolla) and for some reason couldn't get a ping anywhere; some digging showed me that for some reason the modem, which acts as a DHCP server, gives me a local (192.168.x.x) IP address, no DNS servers and no default gateway.

The modem would return pings and the operational web interface showed everything to be fine and dandy, so I spent the next 15 minutes having the most futile conversation I've ever had with a tech support guy. Now as a programmer and reasonably hardware- and network-savvy individual I figured that if a modem and computer restart won't solve the issue it must have something to do with the cable/ISP networks; there was nothing to indicate local failure, so I didn't think to examine the obvious.

The Motorolla modem has a standby button.

I'll be damned if I know why, but it does. And someone pressed it. All it took to get my internet connectivity back is to press it again. Which brings me to the point: it is well known that one of the cardinal sins is vanity, it is equally well known that programmers generally exhibit the three cadinal sins (vanity, hubris and laziness, I think?). So if you're a programmer, whenever you talk to tech support don't be a smartass. You'll save yourself time in the long run.