On 2014-06-04 08:18, Joe Abley wrote:
I don't see the logical jump, here.

A DNS UPDATE client can identify the correct domain controller using the SOA 
MNAME. A recursive resolver can identify the correct domain controller for a 
zone by following a referral chain. Yes, some environments might have split DNS 
design decisions that turn out to make this tricky, but really that's more of a 
reflection of those design decisions than any downstream implementation 
decision.

It's not just that the DNS is split (which Microsoft doesn't even support split zones within Active Directory enabled zones in a traditional "split" format), but rather, that updates are done in a multi-master scenario while sites may have replication intervals in the period of minutes, hours, or days, and updates are best processed by the local AD DNS servers (they are not forwarded upstream using the SOA record or anything else)

In a small environment none of this matters, but in large, multi-site, physically decentralized environments, you might really want local clients doing updates to a local AD server so that their DNS records appear immediately locally and that doesn't happen if you use the traditional "Update the SOA MNAME and wait for the changes to wander down to other servers"

Microsoft's DNS server is using a true multi-master, there's nothing particularly special about the server listed as MNAME, literally any AD DNS server can process updates locally and will ensure that changes are replicated out to appropriate partners.

I'm NOT saying it's the only option -- Just that it's Microsoft's best practice to use Microsoft DNS servers to service Microsoft Active Directory joined servers and clients, and in my experience, staying within Microsoft's best practices is usually wise unless you can articulate a reason to make a difference choice. If you have a practical reason to do something different, do it! I do a lot of non-standard stuff in Windows all the time.

(This isn't even a sales point, Microsoft DNS server is a free component that requires no additional licensing beyond the Active Directory environment itself.)

But at least in this case, I'm more interested in getting the benefits of unbound (awesome resolver performance, DNSSEC validation, pre-fetching, etc) without adding headache (using non-AD DNS for an Active Directory environment), so using Windows DNS internally and unbound for external resolution seems like an ideal configuration unless there are downsides (such as performance)


--
Dave Warren
http://www.hireahit.com/
http://ca.linkedin.com/in/davejwarren


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