Configuring Recursion

In this lecture we’re going to answer the question What is Recursion? We’re going take a look at the reasons why you would enable or disable recursion.

**So what is Recursion? **

**Here is an example: **

If a user opens his WEB browser and types www.serveradademy.com if the clients computer doesn’t know about serveradademy.com the DNS client will ask the **preferred DNS server. **let’s take a look at this clients TCPIP properties, notice the Preferred DNS servers IP address.

If the preferred server or in this case the ISP’s DNS doesn’t know about serveradademy.com, it will make queries to other DNS servers out on the internet.

This asking on behalf of the client continues until the server that is authoritative for serveradademy.com is found, and then the IP address for serveradademy.com is sent back along the chain and ends up on the clients computer. This process is known as recursion.

• Notice if you check Disable recursion notice that also disables forwarders.
• What this means is, if you only want your DNS server to answer queries based upon what it knows then check disable recursion.

In some cases, enabling recursion can be a security issue because your servers are always going out to the internet trying to resolve queries on behalf of clients. And other servers could be using your server to resolve their queries.

**To disable recursion – From your DNS server Open Server Manager **

• Now from tools, click the DNS manager. Right click the DNS server, from Servers properties, click the Advanced tab, and here you can disable recursion.

• Click the root hints tab. Under the Root Hi…