Windows server dns split zone

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Privacy policy. Previously, this scenario required that DNS administrators maintain two different DNS servers, each providing services to each set of users, internal and external. If only a few records inside the zone were split-brained or both instances of the zone internal and external were delegated to the same parent domain, this became a management conundrum.

In some circumstances, the Enterprise DNS servers are expected to perform recursive resolution over the Internet for the internal users, while they also must act as authoritative name servers for external users, and block recursion for them.

Following is an example of how you can use DNS policy to accomplish the previously described scenario of split-brain DNS. This example uses one fictional company, Contoso, which maintains a career Web site at www. The site has two versions, one for the internal users where internal job postings are available. This internal site is available at the local IP address The second version is the public version of the same site, which is available at the public IP address The server Interface is used in this example as the criteria to differentiate between the internal and external clients.

If the server interface upon which the query is received matches any of the policies, the associated zone scope is used to respond to the query. So, in our example, the DNS queries for www. The following sections include example Windows PowerShell commands that contain example values for many parameters. Ensure that you replace example values in these commands with values that are appropriate for your deployment before you run these commands.

A zone scope is a unique instance of the zone. Also, zone transfers are done at the zone scope level. That means that records from a zone scope in a primary zone will be transferred to the same zone scope in a secondary zone.

DNS Policies are divided by level and type. You can use Query Resolution Policies to define how queries are processed, and Zone Transfer Policies to define how zone transfers occur. You can apply Each policy type at the server level or the zone level. Server level policies can only have the values Deny or Ignore as an action.

Using the table above as a starting point, the table below could be used to define a criterion that is used to match queries for any type of records but SRV records in the contoso. You can create multiple query resolution policies of the same level, as long as they have a different value for the processing order.

When multiple policies are available, the DNS server processes incoming queries in the following manner:. Recursion policies are a special type of server level policies. Recursion policies control how the DNS server performs recursion for a query. Recursion policies apply only when query processing reaches the recursion path. Alternatively, you can choose a set of forwarders for a set of queries. You can use recursion policies to implement a Split-brain DNS configuration.

In this configuration, the DNS server performs recursion for a set of clients for a query, while the DNS server does not perform recursion for other clients for that query. Recursion policies contains the same elements a regular DNS query resolution policy contains, along with the elements in the table below:.

Zone transfer policies control whether a zone transfer is allowed or not by your DNS server. You can create policies for zone transfer at either the server level or the zone level. Server level policies apply on every zone transfer query that occurs on the DNS server. Zone level policies apply only on the queries on a zone hosted on the DNS server. The most common use for zone level policies is to implement blocked or safe lists.

A DNS server on an internal network would host a version of the zone that had all hostname mappings with the IP addresses that should be returned to internal clients. DNS Zone scopes allow you to create different subset collections of DNS zone records, with each zone supporting multiple zone scopes and DNS records being able to be members of multiple zone scopes.

When creating a DNS policy to implement split brain DNS, you need to first configure DNS zone scopes with one zone scope containing the host records that should be returned to an external client and another DNS zone scope containing host records that should be returned to internal clients.

Once you have these two zone scopes, you then need to configure DNS policies, one to return records from DNS zone scope to be used by external clients, the other to return records from the DNS zone scope to be used by internal clients. When you create a DNS policy, you can specify how clients are identified as internal on the basis of client IP address or the network adapter that the request arrives on.

If your DNS server has two network adapters, one of which is connected to a perimeter network and another which is connected to the internal network, network interface based policies are the best option. Usual practice is to place all records that should be available to clients on the public internet into the default zone scope and all records that should be available to internal clients in the internal scope.

Once this is done, create a policy that allows access to the internal scope only for queries originating on the internal network interface or client subnets. For example, to create a policy named SplitPolicy that directs clients that address the DNS server on the server interface To get more detail on the process of creating split brain or split horizon zones on DNS servers running Windows Server or Windows Server , consult the following docs.

You must be a registered user to add a comment. If you've already registered, sign in. Hi, Thanks for your post. The asterisk is only used once as the leading leftmost character in a DNS name. If used, an asterisk must always match at least one or more whole labels of a name that precede any non-wildcarded exact characters in the remaining part of the name.

In your case, no support for armlock. The contents of wildcarded resource records conform to normal DNS formats and rules for resource records. For more detailed information, you may check the following article.

Hi Jorge, I know all those processes. My questions was more is it possible because I found not references on Technet. But thanks anyway. Wednesday, August 8, PM. Hi Ace, I appreciate your reply. However, the delegation suggested in the URL is to a specific record, which I already knew. Thanks a lot everyone for the inputs. Thursday, August 9, PM. I understand what you were trying to do. Unfortunately a wildcard won't work that way.

I have never tried that, but give it a shot. Actually I meant to create a blank hostname entry with just the IP. Either way, glad to have helped!