[Today's post comes from the Configuration Manager Writing Team] 

We've been noticing a lot of questions and some confusion about discovery lately.  Discovery hasn't changed much since the early days of SMS, and with priority going to the new features when Configuration Manager 2007 was released, the documentation about discovery was mainly brought over from existing sources. 

When we looked at these questions and reviewed our documentation, we realized that the discovery documentation could do with a bit of polishing.  Well, quite a lot of polishing, actually.  Some of the information was there but not easy to find, or not clearly worded.  Some information was missing.  Some information was no longer valid for Configuration Manager 2007.

For example, the documentation said that discovery was required for client installation and for most feature functionality.  This might have been true in the very early days of SMS, but no longer - only Client Push installation requires discovery and we now have five other client installation methods.  Most functionality in the product doesn't require discovery, although it can help with creating queries and Heartbeat Discovery helps to ensure that the client records are kept active. 

If you've had questions or problems with discovery, we encourage you to read the updated documentation.  However, if you're interested in a quick summary of some of the key pieces of information that customers needed, we put together our "Top Ten Clarifications for Discovery" list.

Top Ten Clarifications for Discovery

1. Active Directory System Group Discovery doesn't discover new resources but discovers additional information about previously discovered computers from the specified locations in Active Directory Domain Services. This information includes the OU and group membership of the computer:

  • This isn't the right discovery method to find computers in Active Directory Domain Services.
  • This is the right discovery method if you need to create collections based on OUs or security groups, and you have already configured Active Directory System Discovery.

2. Active Directory System Discovery must be able to discover the computer account in Active Directory Domain Services and then successfully resolve the computer name to an IP address.

  • To successfully use this discovery method, ensure that your Active Directory computers register their name in DNS.
  • To ensure that this discovery method does not create computer records for computers that are no longer on the network, ensure that DNS is configured for scavenging.

3. Network Discovery must be able to identify the subnet mask in addition to the IP address of a resource.

4. Just because you can discover a resource, it doesn't mean that you can manage it with Configuration Manager. Network Discovery often identifies objects that cannot be managed by Configuration Manager (such as printers), because they have both an IP address and an identifiable subnet mask.

5. Heartbeat Discovery forces the rediscovery of active clients that have been deleted from the Configuration Manager database by the administrator, or by a database maintenance task.

  • If you accidentally delete a computer from the Configuration Manager console, it will automatically "come back" if it is still active on the network. You can either wait for the next Heartbeat Discovery cycle to run, or you can hurry things along by selecting the Discovery Data Collection Cycle on the client Configuration Manager Properties: Actions tab, and click OK.

6. Heartbeat Discovery is the discovery process that submits a client's installation status to its assigned site.

  • The client might be installed but the client state in the Configuration Manager console continues to display No for its Client state if the site hasn't received the client's discovery data record (DDR) from Heartbeat Discovery. This will be the case if the client cannot communicate with its management point.

7. Active Directory discovery methods require that the site server computer account has Read access to the specified Active Directory containers.

  • When you use this account to discover resources in domains other than the site server's domain, the site server computer account must be a member of the Domain Users or local Users group in the other domain.
  • When you use this account to discover resources in another forest, this requires a full forest trust.

8. Discovery can generate significant traffic on the network, especially if the same resources are discovered at multiple sites within the hierarchy. Best practices:

  • Do not enable discovery at a site in the hierarchy if that site and its child secondary sites do not require the discovery data.
  • Modify the properties of the Active Directory discovery methods such that you query specific containers whenever possible.

9. Run Network Discovery only when the other discovery methods cannot find the resources that you need to discover. For example, Network Discovery is the right discovery method for workgroup computers, but Active Directory System Discovery is the better discovery method for Active Directory computers.

10. The approximate size of an individual DDR is 1 KB. It's impossible for us to estimate how much network traffic Discovery creates, because it depends on the number of resources found and how they are discovered. Remember that although each DDR is small in size, these can mount up and discovering a large number of resources can have a significant effect on the network.

Bonus:  We didn't get this clarification into the discovery documentation, because it's not related directly to discovery, but collections.  However, new customers especially, are running into this when they configure discovery and the expected resources do not show up in the Configuration Manager console.  The missing piece of information here is after discovery has run, you won't see the resources in the Configuration Manager console until the collection membership has updated and the console has refreshed.  To do this manually, right-click the collection, click Update Collection Membership, click OK, and then press F5 to refresh the display.


A big thank you to our writer, Brent Dunsire, who helped to collate and research all the customer questions, and also to Brian Huneycutt, who checked and verified our updates.

More information: Our revisions have gone into our March update for the Configuration Manager documentation library:

About Configuration Manager Discovery

- This section about discovery has been updated, with most of the revisions in this topic.  Other topics that have been updated include the following:

Let us know if you have any feedback about these revisions or additional questions that you think the documentation should cover - and as always, send them to SMSDocs@Microsoft.com.

-- The Configuration Manager Writing Team

This posting is provided "AS IS" with no warranties and confers no rights.