DNS in CentOS

**cga** · 04-07-2006, 03:04 PM

Hi all,

I have a small box runing CentOS 4.2 here at school. This is a minimal, text based install. The system works fine, and I can ping and ssh to it from any workstation on the LAN, however, I do not seem to have DNS (i.e. it works from the IP adress, not from the Hostname.

DNS is handled by the router, but I think I am missing something.

Any ideas?

**Compunuts** · 04-07-2006, 03:15 PM

Is bind listed in /etc/host.conf ?

**Outlaw** · 04-07-2006, 03:16 PM

If its an isolated LAN, you probably have no DNS. Can check by doing a

Code:

host www.google.com

. If you think you should have DNS, make sure /etc/resolv.conf contains entries. Otherwise, populate your /etc/hosts on each machine with all the others IPs and names.

**cga** · 04-07-2006, 03:21 PM

Originally Posted by Compunuts

Is bind listed in /etc/host.conf ?

Yes.

order hosts,bind

**cga** · 04-07-2006, 03:24 PM

Originally Posted by Outlaw

If its an isolated LAN, you probably have no DNS. Can check by doing a

Code:

host www.google.com

. If you think you should have DNS, make sure /etc/resolv.conf contains entries. Otherwise, populate your /etc/hosts on each machine with all the others IPs and names.

Yeah, I have /etc/resolv.conf as follows:

nameserver 192.168.9.105
nameserver 192.168.9.1

The second one is the default gateway/router.

Host www.google.com works fine.

**cga** · 04-07-2006, 03:37 PM

OK, if I try to ping the DNS server, I get a host unreachable result. From the CentOS box -- I can ping the DNS from XP just fine.

**Outlaw** · 04-07-2006, 03:44 PM

Does netstat -rn return a gateway?

Code:

netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.0.0.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         10.0.0.1        0.0.0.0         UG        0 0          0 eth0

If not, then see if you can extract the gateway to use from XP box and put it in the Linux one.

If this is a small LAN then chances are, they themselves wont be in DNS. You'll have to depend on hosts files.

**Outlaw** · 04-07-2006, 03:45 PM

whoops, I didnt see your other post.

So it's probably that these machines themselves are not in DNS and you have to rely on hosts files

edit-
it's odd though that you cant ping the dns servers but you can resolve internet addresses.

**cga** · 04-07-2006, 03:54 PM

Originally Posted by Outlaw

whoops, I didnt see your other post.

So it's probably that these machines themselves are not in DNS and you have to rely on hosts files

edit-
it's odd though that you cant ping the dns servers but you can resolve internet addresses.

I can't resolve them from a browser or ping an address by name -- only by IP address. It's weird. I must be missing something.

**cga** · 04-07-2006, 03:59 PM

Originally Posted by Outlaw

Does netstat -rn return a gateway?

Code:

netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.0.0.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         10.0.0.1        0.0.0.0         UG        0 0          0 eth0

If not, then see if you can extract the gateway to use from XP box and put it in the Linux one.

If this is a small LAN then chances are, they themselves wont be in DNS. You'll have to depend on hosts files.

Hmmmm... I get a gateway alue from netstat that ends in .254. ipconfig on XP gives the gateway as .1

Should I tweak my routing tables to reflect the XP value for the last octet?