Which server should be listed in the preferred DNS entry

[TwistedHelixis]

In the adapter settings,

 

Currently on DC1 I have the preferred DNS as DC2 and DC1 as the alternate.

 

Then on DC2 I have DC1 as the preferred and DC2 as alternate.

 

Is this correct. Every time I read a forum about this someone always says it's the other way round, or the opposite.

[Michael]

Always point to itself first, then another server on your network second, providing they're all DNS servers of course!

[Davit2005]

IMO Local DNS in Prefered (itself) alternative DNS in alternate, if the DNS server is looking at another DNS server as it's preffered which could be down/offline I can't see the logic.

[mikkydoos]

@TwistedHelixis

 

You've got it set up correctly.

 

Thats the way MS say to do it.

 

 

EDIT:

 

Here.... http://serverfault.com/questions/394804/what-should-the-order-of-dns-servers-be-for-an-ad-domain-controller-and-why

Edited March 3, 2016 by mikkydoos

[Michael]

An alternative DNS server nominated as its preferred makes no sense to me either.

 

I'm curious to know then @mikkydoos if you have multiple sites connected via slow/average WAN links and a physical server at each, would you still nominate an alternative DNS server as its preferred, despite being over a slow/average WAN link?

 

Instantly in this scenario, you will get DNS failures or DNS resolution will definitely be slower. Even in a local environment, everything all on site and say each server is connected to a different switch in your LAN - again, a switch goes down, again you'll end up with DNS errors and slow resolution(s).

[mikkydoos]

Indeed. As @Davit2005 says.. It is illogical.

 

I just stated its the way MS recommend it is done. Thats all. Its to prevent replication issues I think I recall.

[Davit2005]

Indeed. As @Davit2005 says.. It is illogical.

 

I just stated its the way MS recommend it is done. Thats all. Its to prevent replication issues I think I recall.

 

But since when has logic ever appliied to IT let alone MS

[mikkydoos]

But since when has logic ever appliied to IT let alone MS

 

Oh, always. They're the most brilliant company to ever exist. My system never ever goes wrong with Microsoft products on it.

[Paid_Peanuts]

https://blogs.technet.microsoft.com/askds/2010/07/17/friday-mail-sack-saturday-edition/#dnsbest

 

There is a bit of explanation as to why it is best practice to point preferred DNS to alternative DNS server first with itself as secondary.

[Michael]

https://blogs.technet.microsoft.com/askds/2010/07/17/friday-mail-sack-saturday-edition/#dnsbest

 

There is a bit of explanation as to why it is best practice to point preferred DNS to alternative DNS server first with itself as secondary.

 

It shouldn't point to itself due to performance issues? As I say, it doesn't address the large WAN scenario I gave an example above. DNS requests would be dramatically slowed down going down WAN links, along with other traffic.

 

The only exception to this rule of course is DNS requests for external - most likely websites, as this is controlled by your Forwarders. Setting the preferred DNS to another server first will only make the request bounce off more internal servers before requesting outside your LAN. If you work by this logic in a big network, you'd essentially be creating a lot more traffic for no good reason. I really disagree doing it the way in the above link

[mikkydoos]

They say it's to prevent islanding.

 

I think it means that records could become out of sync between DNS servers.

 

Out of interest I just created a record on DC1 and it took a while for it to replicate on DC2. The same for deleting it.

 

I had to reload the zone to get it to pick up the new record. That's not right is it? Surely it should replicate like SYSVOL and update immediately ??

[Michael]

They say it's to prevent islanding.

 

I think it means that records could become out of sync between DNS servers.

 

Out of interest I just created a record on DC1 and it took a while for it to replicate on DC2. The same for deleting it.

 

I had to reload the zone to get it to pick up the new record. That's not right is it? Surely it should replicate like SYSVOL and update immediately ??

 

DNS updates every 15 minutes I believe, this is normal.

[mikkydoos]

DNS updates every 15 minutes I believe, this is normal.

 

This is true. Just checked the reload time

[Michael]

I can only imagine Islanding would/could occur if you're using the same subnet over a very large WAN, when really you should use different subnets which of course splits off into different DNS Zones.

[mikkydoos]

Hmm.. Now I'm wondering whether I should be using the adapters IP address or 127.0.0.1 for loopback - whether it is primary / secondary or whatever.

[Michael]

Well thinking about it 127.0.0.1 wouldn't use DNS (I think that's right), whereas using the adapter's native IP would show DNS issues quicker (again theoretically).

[TwistedHelixis]

Even after reading all your posts I am still a bit confused, as everyone seems to do this differently.

 

So if both DC's are next to each other should I leave DC1 pointing to DC2 as preferred or change it?

 

Cheers

[mikkydoos]

@TwistedHelixis

 

Either way works. I personally would leave it like you have it. The others may disagree. If it ain't bust, don't fix it - unless you're getting poor DNS speeds.

 

(After reading it up) some say don't use a 127.0.0.1 address, use a proper IP.

 

Try both ways...

 

Run dcdiag /test:dns

 

See if you get any issues.

 

These are mine on DC1 ---> Reverse them for DC2... they work a treat.

 

[ADMaster]

I think the way you have it is correct. and i disagree with the WAN scenario.

The OP is speaking of setting the adapter DNS. This will effect the servers communication back to the the other sites, and any dns lookups the DC must do

The clients at the site will all communicate with the local DNS server and where it resolve client requests from is set in DNS forwarders.

The DNS forwards are typically up stream ISP / LEA dns servers.

[TwistedHelixis]

What if you are installing a new DC and you have 3 running for a while, how would they be set

 

DC1 preferred = one of the other DCs

DC1 Alternate = DC1

Where would you put the 3rd DC?

 

and so on for the other 2 DCs

[mikkydoos]

Have a look here @TwistedHelixis

 

Another guy had a DNS problem with the same scenario as yours. I think this sorted it for him.

 

http://www.edugeek.net/forums/windows-7/165365-some-clients-not-updating-dns-records.html

[TwistedHelixis]

Hmm.. Now I'm wondering whether I should be using the adapters IP address or 127.0.0.1 for loopback - whether it is primary / secondary or whatever.

 

Best practice analyzer chucks up an error for me using server IP saying DNS needs loop back address to function properly. hmmm also.