host lookup failed can't use Mozilla or email but ping is OK
 

I have installed Redhat 9 (kernel 2.4.20-6) as dual boot with Win XP. Am using Gnome desktop. Have external serial modem on com 1. I seem to have modem and ISP more or less set up OK as I can ping and get a response. When I try to use Mozilla I get "host lookup failed" after a long time. DNS server address came from my ISP and is 198.6.100.194. Tried to set up Evolution email and got similar message when it tried to go to my pop server. In my network profile, I only have the modem connection (ppp).

I am guessing it is maybe a firewall problem or maybe I need to tell Mozilla and Evolution to use the modem networking, but I don"t know how to proceed.

Any suggestions would be appreciated.

Thanks,

Ken

Have a look in /etc/resolv.conf and see if your dns servers are actually there. It should look like -
nameserver 158.43.240.4

Before I activate my modem network connection, /etc/resolv.conf has the DNS IPs that I manually entered. After activation, it has the DNS IPs that it presumably got from my ISP. I can ping these IPs and they respond. Beyond that, I don't know anything about them. I will try to find an IP of a normal internet site (using Windows as I am now) and see if I can connect to it with Mozilla.

If I put an IP address into Mozilla, I can go to that address and function OK until the next need for a name lookup. This would seem to suggest that my problem is DNS not working correctly. Does anyone have any suggestions on what to try next to fix it?

Problem Solved
 

I figured it out! The firewall security was too high. That was what I suspected at first, but it took me this long to figure out how to change the firewall. In redhat 9 command is: "/usr/share/redhat-config-securitylevel/redhat-config-securtylevel" run as root.