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How will changing the gateway address on server r2 2008 affect DNS and domain

We are in the process of getting another ISP in our office. The purpose is to get a faster speed and also setup a failover at a later time with the slower connection. We have a windows server r2 2008 that is the domain and DNS for our network. At this time, I have both internet connections plugged into our network via a switch. Our original ISP connection is on a router with 192.168.1.1 and the new ISP is on another router with 192.168.1.254. The domain/DNS is on 192.168.1.2 and has its gateway set to 192.168.1.1

I currently have my PC statically assigned to go to .254 for the gateway and .2 for the DNS. I want to move all of the other PC's over to this connection tomorrow. I want to make sure that I am not over-simplifying my next move. It seems to me that I should be able change the DNS servers gateway to 192.168.1.254, then have all users log off the domain and log back on and their PC should get a dynamic address and the DNS should automatically rout their traffic to the .254 gateway.

Am I right n assuming this, or am I missing some steps that will affect this transition?

Thanks
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Sushil Sonawane
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If you change your domain server gateway there is no requirement to logoff your client machine.

In your environment dhcp available then only modify your gateway 192.168.1.1 to 192.168.1.254 in dhcp console.
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Rob Williams
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RobWill,

Thanks for your insight.

I have a question on the DNS Forwarders. It appears that the DNS server does not have any forwarders set from the previous ISP's DNS. I have seen some people say that there is no need to enter the ISP's DNS information in the Forwarders menu. Do you feel that it is better to have the ISP's DNS servers entered in this menu? What are the advantages or disadvantages of entering DNS ifo in the Forwarders menu?

Thanks
There are two options; Forwarders and Root Hints.  The IT community is split as to which is the better option.  Nothing at all wrong with leaving the way it is, but if forwarders are present and you change ISP's there might be some delays resolving names if you don't update them.

A couple of 'side notes':

1) There were some known issues with resolving top level domain names using root hints that could be fixed by using forwarders or a registry edit:
http://support.microsoft.com/kb/968372

2) There is a  known issue with "Use root hints if no forwarders are available" which actually configures the opposite behavior:
http://technet.microsoft.com/en-us/library/ff807391(v=ws.10).aspx#feedback
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RobWill,

Thanks for all the help. One last question, I added the new gateway to the DHCP server in option 3 as you had stated in your first post. I see that you can have multiple gateways listed in the #3 option. If I have our new gateway at the top of the list, and keep the old gateway in this list as the second option, will this cause any problem? I have this setup going at this time. When I restart a pc and it pulls a new DHCP the PC shows two gateways listed with .254 first and .1 as the second. It appears to me that the PC will go out the .254 gateway, unless this is not available and then it will fail-over to the .1 gateway.

Thanks
>>"If I have our new gateway at the top of the list, and keep the old gateway in this list as the second option, will this cause any problem?"
Yes that will cause problems.  Sorry if I implied you can add a second gateway.

Multiple gateways do not work in Windows as they should.  In theory a "metric" can be assigned to a gateway which sets it's priority, but what happens is the highest priority gateway  is used until it fails, even for a second or two, then the device switches to the next priority but it will never switch back until you do a reboot.  Windows will even warn you multiple gateways are not supported if you try to statically assign one to a PC.