Help, bizarre networking problem

[Dave N500 CHM]

Afternoon all

Came in this morning to find out that three machines had lost their internet connection. They had actually lost everything so I started looking for a dodgy connection. Which I found and re-connected.
Their network comes up but still no internet.
So now I suspect the router or firewall. Disabled firewall, no difference, reset router, no difference.
All other machines connect fine, just these three which are all in the same room into one hub which is linked into another hub which is linked to the router.
Now the really bizarre bit is I realised that these machines were receiving emails while I was working on them?????

I can log into the router from any of them and see that it is up and working as it should be. Can't be the machines as there is more than one of them and they were working yesterday.

Any ideas?

Thanks for any help

[nickjm]

If it was just the one machine I'd say it was possible spyware.

Are they able to ping anything beyond the router?

[BaconBonce]

Try an IPCONFIG/FLUSHDNS at the command line assuming 200x/XP machine

[Dave N500 CHM]

nickjm said:

If it was just the one machine I'd say it was possible spyware.

Are they able to ping anything beyond the router?

No that can't ping a thing other than the local machines and the router

[Dave N500 CHM]

BaconBonce said:

Try an IPCONFIG/FLUSHDNS at the command line assuming 200x/XP machine

Yep, two 2000's and 2000 server. Can you elaborate a bit more on this please

[sheets tabuer]

can you ping a website from a command prompt ie ping www.google.com

Pinging www.l.google.com [216.239.59.147] with 32 bytes of data:

Reply from 216.239.59.147: bytes=32 time=122ms TTL=246
Reply from 216.239.59.147: bytes=32 time=38ms TTL=246
Reply from 216.239.59.147: bytes=32 time=45ms TTL=246
Reply from 216.239.59.147: bytes=32 time=87ms TTL=246

if not try pinging an ip address ie ping 216.239.59.147

Pinging 216.239.59.147 with 32 bytes of data:

Reply from 216.239.59.147: bytes=32 time=40ms TTL=246
Reply from 216.239.59.147: bytes=32 time=55ms TTL=246
Reply from 216.239.59.147: bytes=32 time=40ms TTL=246
Reply from 216.239.59.147: bytes=32 time=80ms TTL=246

if you can ping the IP address but not the name it's probably a DNS issue.

eta missed the bit where you said can't ping beyond the router cos I'm blind

Edited by sheets tabuer on Friday 1st June 16:50

[The Griffalo]

Chances are e-mail is a red herring (SMTP/Exchange server is inside your LAN) I'd reboot the switch first and then the router if nothing else has been reconfigured on your network. Try the simple stuff first

If that doesn't work is your network a single subnet or do the switches have routing capability? Sounds like the router has lost it's route back to the affected machines.

[BaconBonce]

Dave N500 CHM said:

BaconBonce said:

Try an IPCONFIG/FLUSHDNS at the command line assuming 200x/XP machine

Yep, two 2000's and 2000 server. Can you elaborate a bit more on this please

Sure, just drop to a command prompt in Windows on one of the problem PC's and type 'ipconfig /flushdns' (without the quotes) and hit enter. This will clear out the DNS resolver cache on the machine.

Then try t'internet again.

Edited by BaconBonce on Friday 1st June 17:40

[Dave N500 CHM]

Thanks people, will try everything when i get back on monday now.
But i will keep my fingers crossed it sorts itself over the weekend

[Dave N500 CHM]

An afternoon update

Thanks for your help, seems it is a dns issue. I can ping outside of the router, don't know now why I thought I couldn't at the time.
I was able to ping google's IP and when I put the IP into a IE the google page popped straight up.

So my next question is how the hell do I fix it?

Thanks again

[The Griffalo]

From a command prompt.

ipconfig /all. Check to see what's different between working/non-working machines.

Also check the internet explorer proxy settings. It's one or other of these that's causing the problem.

[Dave N500 CHM]

Thanks for your help and quick replys Rob but the machines are working now.

I called up my provider to check the dns address and he gave me a new one to try and sure enough they worked straight away.
He couldn't explain why all the other machines next door work though.

[Danielson]

good to hear you have it working now..

just for anyone who needs to test internet connectivity in future and rule out DNS as a problem then ping 4.2.2.2 its a DNS box as it happens but the owner lets it respond to pings and it pretty easy to remember the address..

[Dave N500 CHM]

Danielson said:

good to hear you have it working now..

just for anyone who needs to test internet connectivity in future and rule out DNS as a problem then ping 4.2.2.2 its a DNS box as it happens but the owner lets it respond to pings and it pretty easy to remember the address..

Ahhhhhh fankooo Danielson

[The Griffalo]

Normally your server would be your DNS and act as a forwarder to your ISP for any lookups outside your LAN.