DNS problems

[Lee Sitton]

We are running 10.2 on a 9000 server and have recently changed ISP's. The problem is that when the Leased line to our ISP goes down, the PC's on the LAn can't connect to the 9000 for about five minutes and then the coneections are problematic (missing data etc). We have looked at our routing tables which are:

127.0.0.1 127.0.0.1 UH 8 2744 lo0 4608

194.202.120.25 127.0.0.1 UH 2 4603 lo0 4608

213.131.170.10 194.202.120.19 UGHD lan0 1500

default 194.202.120.29 UG 0 7 lan0 1500

194.202.120 194.202.120.25 U 21 203872 lan0 1500

194.x.x.x is LAN, 213.x.x.x is ISP DNS1, 194.x.x.25 is the server in question.
Can anyone please tell me why this server needs to have a continous connection to the internet for it to allow others to access it? Is IP forwarding the problem or the fact that the routing tables are not correct? We also get what appears to be dynamic routing as the tables change throughout the day..but dynamic routing is definitely switched off! This has all happens since we disconnected our old proxy firewall, changed ISP's and replaced it with a sonicwall pro 100.
We appear to be up-to-date with our patches.
Please help.

Andrew

[Steven Sim Kok Leong]

Hi,

Did you enable gated or rdpd? These are routing protocols that facilitate a failover of default route if the primary router or gateway is down.

You can check by:

# ps -fae|grep gated
# ps -fae|grep rdpd

Hope this helps. Regards.

Steven Sim Kok Leong

[Steven Gillard_2]

The pause when users connect is likely to be DNS related. You might like to configure your /etc/nsswitch.conf file so that the /etc/hosts file is searched before DNS, and also make sure you have entries in /etc/hosts for all PC's on your LAN.

Regards,
Steve

[Jeff Schussele]

Are all the PCs on the same subnet?
If not you have to setup & then define a local router/gateway to serve as a backup when the ISP line goes down. I would also recommend you setup a local DNS server (UNIX or NT - UNIX preferred) to stand as a backup in same scenario.

Rgds,
Jeff

[Anil C. Sedha]

Hi Lee,

I agree with Steven, when he says that /etc/hosts file should appear before dns. The reason for this is that your entry in /etc/nsswitch.conf file right now would be showing as follows :

hosts dns [NOTFOUND=continue UNAVAIL=continue] files [NOTFOUND=continue UNAVAIL=continue]

make it as below

hosts files [NOTFOUND=continue UNAVAIL=continue] dns [NOTFOUND=continue UNAVAIL=continue]

I hope this will resolve your problem. Also make sure that you have all the entries of the pc's in your hosts file. If you have a large setup is NIS enabled. In that case you shall have to give the NIS [NOTFOUND=continue UNAVAIL=continue] before dns entry.

PS : Don't forget to award points if this resolves your problem.

Regards,
Anil

[Anil C. Sedha]

Hi Lee,

I agree with Steven, when he says that /etc/hosts file should appear before dns. The reason for this is that your entry in /etc/nsswitch.conf file right now would be showing as follows :

hosts dns [NOTFOUND=continue UNAVAIL=continue] files [NOTFOUND=continue UNAVAIL=continue]

make it as below

hosts files [NOTFOUND=continue UNAVAIL=continue] dns
I hope this will resolve your problem. Also make sure that you have all the entries of the pc's in your hosts file. If you have a large setup is NIS enabled. In that case you shall have to give the NIS [NOTFOUND=continue UNAVAIL=continue] before dns entry.

PS : Don't forget to award points if this resolves your problem.

Regards,
Anil

[Anil C. Sedha]

Hi Lee,

I agree with Steven, when he says that /etc/hosts file should appear before dns. The reason for this is that your entry in /etc/nsswitch.conf file right now would be showing as follows :

hosts dns [NOTFOUND=continue UNAVAIL=continue] files [NOTFOUND=continue UNAVAIL=continue]

make it as below

hosts: files [NOTFOUND=continue UNAVAIL=continue] dns
I hope this will resolve your problem. Also make sure that you have all the entries of the pc's in your hosts file. If you have a large setup is NIS enabled. In that case you shall have to give the NIS [NOTFOUND=continue UNAVAIL=continue] before dns entry.

PS : Don't forget to award points if this resolves your problem.

Regards,
Anil