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I am using Windows server 2003. My primary domain controller is my DNS. I want to make an internal subdomain for my main website, like a staffpage.oursite.com . However I do not have a zone for oursite.com on our DNS and if I create a new one, the webpage oursite.com will use our DNS instead of our ISP's DNS. How do I make a subdomain and any records that are not held in my DNS to resolve using the ISP? we have a lot of A records on our host and I just want to resolve one cname internally.

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2 Answers 2

You can use your internal subdomain as a parent for additional child domains that you create to manage divisions within your company.

For example, to implement an internal subdomain of the external domain example.com:

  1. Configure the external DNS server with the namespace example.com. This server contains a static zone with only records for servers that are to be available publicly on the Internet. These records would typically include such servers as www.example.com, ftp.example.com, and so on.

  2. Configure the internal DNS server with the namespace corp.example.com. Note that while the internal namespace is a subdomain of the external namespace, the internal zone is not delegated from the external zone. That is, the external server does not have a delegation record.

  3. Register all hosts in the organization's internal network in the corp.example.com namespace, either in the corp.example.com domain or in child domains within that namespace. For example, a server for the sales department might have the fully qualified domain name of salesvr1.sales.corp.example.com.

  4. Disable dynamic updates on the external server because no computers in the company's internal network should be registered in the external namespace.

  5. Configure the internal DNS server to forward Internet queries to enable internal hosts to resolve external (Internet) names. You can do this in one of two ways:

    • Configure the internal DNS server to forward to the external server, which enables recursion on the external server. In addition, you can configure the internal server as a secondary server to the external server. This enhances the security of the internal network by ensuring that the internal server never makes a query directly on the Internet.

    • Configure the internal DNS server to forward queries to the Internet service provider's DNS server. This method enhances security on the external server because it makes it possible to disable recursion on the external server.

Instead of using forwarders, the internal DNS server may be configured simply to use the standard Internet root hints to resolve Internet names. The DNS server is configured with the list of standard root hints when the DNS server role is installed. This option is the least secure, however, because it requires the internal DNS server to be able to access DNS servers on the Internet.

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I don't understand why using root hints reduces security (your last paragraph), could you please clarify? Other than that, helpful answer :-) –  poplitea Dec 27 '11 at 9:40
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Because of the additional fields that can be added to DNS responses, attackers could in theory send your internal computers bogus DNS responses that would cause trouble. If you keep your internal DNS separated from your external DNS you in theory could mitigate some of this. Obviously, you need to pull from the public Internet at some point, but I think avoiding root hints limits one more attack vector. –  n1reu Dec 27 '11 at 19:19

You can setup split DNS or you can just use your internal domain name to make things simpler. A less elegant solution would be to create an hosts file entry on all of your clients. The latter is a lot of work and headache, I would just use the internal domain name.

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