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DNS

By sunadupadhye ·
Hi Team,

Actually, we have more than 10 DNS Servers and 5 WINS Servers.
Otherside more than 500 application servers and some other servers almost 250. All these servers are using DNS/WINS service.

Now problem is 4 DNS servers and 2 WINS are going to be decommissioned; but we dont know which app/other servers are using which dns/wins server as primary & secondary which is configured manually. Now before decomm we want this set of information to remove dns/wins dependencies of servers which going to be decommed.

please help me as centralize solution.

Thanks,
Sunad

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Powershell works

by WhoFsckingCares In reply to DNS

We just did something like this. Given a list of your servers in CSV format, you can do this to find who has what DNS servers set:

t = Import-Csv C:\TEMP\PS\Servers.csv
$t|
%{
$computer = $_.Name.trim()

$DNS = WmiObject win32_networkadapterconfiguration -computername $computer -ErrorAction SilentlyContinue |?{ ($_.IPAddress -like '192.168.*')}
$x = $DNS.DNSServerSearchOrder
write-host $computer " : "$x

}

Then, if we were looking to make sure that 192.168.1.1 and 192.168.1.2 were in the DNS settings, we had:

$t = Import-Csv C:\TEMP\PS\Servers.csv
$t|
%{
$computer = $_.Name.trim()
$lan = Get-WmiObject win32_networkadapterconfiguration -computername $computer |?{($_.DNSServerSearchOrder -notcontains '192.168.1.2') -and ($_.IPAddress -like '192.168.*')}
$dns=@("192.168.1.1","192.168.1.2")
$lan.SetDNSServerSearchOrder($dns)

}

You can modify this to your own preferences.

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Reponse To Answer

by sunadupadhye In reply to Powershell works

Very thanks for solution above but we have win2003 domain environment.....

but we have 2008 member server, so will that work ?

Thanks again :)

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Sniff, log and fake

by leifnel In reply to DNS

You can set the DNS-servers to log which clients are querying it, or you can setup a network sniffer on the DNS-Server to see the same.

Just only kill one DNS-server at the time.
There still is the risk that some client is using one of the decommisioned servers as secondary DNS, but you will only know if that client's primary DNS dies.

If you run wmvare or other virtualization, you can make a forwarding DNS-server with all the ip's of the decommisioned servers, and in that log discover who still uses the old servers. Heck, a forwarding dns does not use much cpu-power, and you could have it around for long time until you are sure noone is using it anymore.

Dunno about wins though...

Of cause, if it is on a private network, you can just give the existing DNS servers the IP's of the decommisioned servers as secondary ip's, but that is a dirty solution.

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I know this may seem like too basic an answer, but

by Deadly Ernest In reply to DNS

why not just set your routers to redirect traffic from the old servers to the new ones via entries in the routing table?

In a worst case scenario of not being able to find what accesses what, just slip an extra NIC into the servers you're keeping and give that NIC the IP address of the old server you're taking out.

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Reponse To Answer

by WhoFsckingCares In reply to I know this may seem like ...

I agree that is an easy solution, made easier by the fact that Win2003 servers will support multiple IPs on a single NIC. As far as whether the script will work in a W2K3 domain, I don't know. Try the first half, it's read-only, then if it works try the second part with a list consisting of one server. I don't see any career-limiting consequences coming out of that.

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Reponse To Answer

by Deadly Ernest In reply to I know this may seem like ...

WFC,

I know the multi NIC concept works, well I should say used to work, as it's one I often had to do back in 2000 and 2001 as a temp fix for some issues on a very complex network. However, I was usually doing it on Unix or Linux servers, so not all that sure if Windows servers can handle it. The few NT servers we had then could do it if set up from the start, but a later change basically meant a total server rebuild where as we could reconfig the Unix and Linux ones in a few minutes and they worked.

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