There's probably a very simple explanation for why I'm having this problem, but I don't know what it is.

Cable modem, Linksys router connected to WinXP box and Mandrake 9.1 box. Windows machine works flawlessly in every way on both LAN and internet.

Linux machine can ping Windows machine (and be pinged as well), can access the router, and can access any machine on the internet via ping or Mozilla, but ONLY if I use the dotted quad. Any time I try to ping foo.com or type foo.com into the browser address, it behaves exactly as if it weren't connected to the 'net.

The router assigns internal IP's via DHCP, but I've tried overriding this on the Linux machine by assigning a static 192.168.1.102 and it makes no difference. The route command shows all the proper interfaces and gateways, etc. - but there's a longish (10-15 sec) delay between listing "192.168.1.102", "127.0.0.1" (then delay, then) "default." Don't know if this is normal.

I don't know if it makes a difference, but connecting the linux machine directly to the cable modem (making no other changes) and rebooting fixes the problem.

I suspect a DNS problem somewhere, but I don't know where to look.

Thanks in advance,

William

Edit your /etc/resolv.conf and manually spcify your ISPs DNS servers. eg:
nameserver 123.45.67.89

also, look for a firewall setting on the router that may be accidentally blocking dns querries.