Ok, apologies in advance for what may become a long and rambling post.
We're in the process of having a new network installed over the summer and have hit a fairly large problem.
This is the situation, the existing network is in place and all is working. The new network is in place, all servers are up and running however at this point there is no connection to the Internet, but there is a connection to the Internet on the old network. If we bridge The two networks and connect them to each other the old servers and the new servers can see and talk to each other, however we lose our Internet connection.
As soon as we remove the bridge, the Internet connection is restored and works again.
Naturally with two networks, we have multiple dc's with two sets of dhcp and dns servers, two separate default gateways, however the ip ranges are the same. We've checked the ip's and there are no conflicts.
I assume this is going to be a dns issue somewhere, but I've no idea on where to start to try and fix issue.
Anyone got any ideas?
Proxy settings are all ok, as I say we don't make any changes other than to connect the two networks physically and it just stops working :-(
Are both DNS servers in sync?
What does a tracert to say, BBC - Homepage tell you? Does it stop at any point?
How are using a proxy - wpad/pac or set through GP? Try setting it manually to an IP address to rule out DNS glitches
Do you loose internet access for both networks or just one?
We've done the setting of the proxy manually and by gp and neither makes any difference....
What do you mean about the DNS servers being in sync? Do you mean do they contain the same entries?
Is the gateway ip the same for both?
I think the bridge is breaking because you have the gateway set at 2 places. Try removing the gateway from old network when bridging to new network and see if they then route to the gateway for the new network. If they are all in the same subnet/range dual gateways will cause issues I *think*.
If a trace works from both networks and mail is flowing, it really points to an issue with your proxy server. Do you proxy everything or just www, if you can try something you don't proxy to confirm like ftp or ssh.
I'll get hold of actual configuration tomorrow and check ISA for what we actually proxy and come back.
Thanks for everything so far
IE 10 issue ? Try firefox or go back to IE9
IE10 does not like proxies
Ok tried it again this morning, definitely not a browser issue as we've tried it with IE, chrome and Firefox.
I've had a problem where one DNS server returned one address, the other DNS server returned a different one (for an internal machine). I had to delete the cached lookups.
server <ip address of one of your DNS servers>
<name of your proxy server>
and see what address is resolved. Then
server <ip address of your other DNS server> and type the name of the proxy again, check it's the same, correct, address.
Last edited by jinnantonnixx; 1st August 2013 at 09:51 AM.
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