Can't Resolve DNS IP

shipon_97 · 08-25-2006, 10:15 PM

Dear Friends ,

I got a strange problem . I am working in an ISP . I have a Client , I gave him support using Redhat Enterprise Linux 4 Machine . After Installing the OS perfectly , I put IP into eth0 lan and also I get ping my webserver , Mail server , Gateway Router , DNS server everything .

Now the problem is : I get to ping my DNS server but I cannot resolve DNS IP from this machine i.e., using my DNS server IP into "/etc/resolve.conf" I can't browse any website . And I cannot get ping "www.yahoo.com " . The machine shows that it cannot find this domain . And I don't find any result using "nslookup "

But from another client side , internet browsing and others are OK . I don't understand what is the problem . Can anybody plz help me about this regards .

Thx.....

zeroability · 08-25-2006, 10:51 PM

In your DNS server configuration you need to add a forwarder to your WAN DNS server IP's. I am not sure what RH uses to manage your DNS server (BIND4 or named) but you basically have to tell the server, I have a LAN that resolves intranet host requests here and forwards them to the name service records on WAN servers. For the local server to have access to the nameservices on another server external or internal the ip addresses and the doman search paths need to be entered in /etc/resolv.conf, unless the server receives it's address information by a DHCP server with all the ip's entered in the server for gateway, DNS, etc. Also, the server has to know where the default gateway to the internet is. If you type:

Code:

 /sbin/route

it should give you a print of all static routes in the routing table. You may need to add the default gateway using (I think):

Code:

 (must be superuser) 
/sbin/route add default gw xxx.xxx.xxx.xxx 
(this would be whatever your default gateway is)

RH usually has graphical ways to configure it also. If you have a firewall enabled on this server, port 53 must be accessable bidirectionally across your LAN and WAN subnets.

Did I miss anything? Ok I think I covered most contingencies.