Configuration Management Database (CMDB) Fundamentals (Course): Lesson2 (identifictaion )

ImedCG
Tera Expert

4 hours ago - last edited 4 hours ago

 Lesson2: Identification and reconciliation Engine OverView: Identification Rule Example
https://learning.servicenow.com/lxp/en/pages/learning-course?id=learning_course&course_id=c03ca22847...

The identification process follows these steps:

  1. Attempt to match using both serial_number and serial_number_type.
  2. If no match is found, attempt to match using serial_number only.
  3. If no match is found, attempt to match using name.
  4. If no match is found, attempt to match using mac_address AND name.

However, this logic does not make sense for Step 4.
Since Step 4 also requires a name match, it will automatically fail if Step 3 already failed on the same name value.

Based on this, it seems Step 4 should either replace Step 3 or the matching condition in Step 4 should be revised if the intention is for Step 4 to succeed even when Step 3 fails.

Could you please confirm the intended behavior?

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Sneha KH
Tera Guru

4 hours ago

Hello @ImedCG ,
The reason Step 4 is not redundant is that it is typically targeting a different table than Step 3. While Step 3 checks for a match on the CI's Name (the Server itself), Step 4 is usually a "Related Entry" check that looks at the Network Adapter table. In this context, "Name" in Step 4 refers to the name of the Network Port (like eth0 or Ethernet 1) combined with its MAC Address. Since a match on a specific network card can uniquely identify the parent Server even if the Server's main name has changed, Step 4 acts as a critical "Plan B" that remains valid even when the Step 3 "Name" check fails.

If you want to relate it with real-world example then,

Think of it like identifying a person:

  • Step 3: You try to identify a person by their Full Name (e.g., "John Doe"). If you can't find a "John Doe" in your database, this step fails.

  • Step 4: You try to identify that same person by looking at their Credit Card. A credit card has its own Name printed on it (e.g., "Platinum Card") and a Number (the MAC Address).

Even if the person changed their legal name (causing Step 3 to fail), you can still identify them because that specific "Platinum Card" is still linked to their profile in your records.

 

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