Dns Problem

[gee7022]

Hi Guys we seem to have a dns issue if you ping a name it works for a while and then you just get a request timed out. I've tried changing the dns server address but then it only works for about 20 seconds and then stops working again. I'm currently using telkom as my ISP so it's their DNS servers, anybody else have this problem?

 

[Carlhead]

sounds like a router issue;

are your IP addresses assigned using DHCP? Are you sure someone's machine on the network isn't "stealing" / conflicting with the router.

 

[gee7022]

We are using DHCP and static IPs.
One question how can a computer conflict with the router?

 

[Carlhead]

Ez, someone inadvertantly assigns it the same IP as the router e.g. 192.168.1.1

Then you'll get issues like the internet working interittently... the best way to test this is to ping the router repetitively i.e. ping <<routerip>> -t then switch off the ADSL router, if the ping reply continues then you know another computer on the network has the routers IP as well.

Then it's a simple case of asking everyone whether there computer has said anything about a IP conflict.

It could however be something altogher different...

If the prior wasn't the case, perhaps try specifiying DNS server in the IP settings of each machine... if it's a SAIX based ISP you're connecting to I recommend:

196.43.1.11
196.25.1.11

Just a shot in the dark though

 

[gee7022]

Thanks for your help so far
The thing is everyone in the office knows the router ip and putting the dns in every computer is going to be a headache. And the main thing is it only started happening a few days ago. I can also ping international sites and some local ones but not all of them. But now I changed my DNS servers to IS servers and all seems fine know. Any ideas why this would happen?

 

[Carlhead]

Thanks for your help so far
The thing is everyone in the office knows the router ip and putting the dns in every computer is going to be a headache. And the main thing is it only started happening a few days ago. I can also ping international sites and some local ones but not all of them. But now I changed my DNS servers to IS servers and all seems fine know. Any ideas why this would happen?

Really depends on what DNS servers were used previously... maybe they're having issues?

I never let my clients routers get thier DNS settings from SAIX. I always specifiy, if not in the router then in the IP settings of each machine.

I've had so many problems with machines getting random DNS server addresses from their routers... i.e. 168.257.x.x or something of the sort.

 

[gee7022]

Really depends on what DNS servers were used previously... maybe they're having issues?

I never let my clients routers get thier DNS settings from SAIX. I always specifiy, if not in the router then in the IP settings of each machine.

I've had so many problems with machines getting random DNS server addresses from their routers... i.e. 168.257.x.x or something of the sort.

Hi Thanks for your help I know now not to use SAIX DNS anymore I think it only happened when I let the router get the DNS automatically. The IPs you gave me can I use them permanently?

 

[Carlhead]

yeah, those are the ones I use at all my clients... there are no plans to decommision them in the forseen future.