Can I use a comparison mask for NCM RUNNING VS STARTUP configurations?

Document ID : KB000109095
Last Modified Date : 02/08/2018
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Introduction:
we are using the NCM config backup for startup and running configuration comparisons but are still getting "STARTUP AND RUNNING CONFIGURATIONS ARE DIFFERENT" alarms based on a part of the startup configuration that is supposed to be masked by the mask configuration.

 
Question:
Is the NCM comparison mask taken into account for running vs. startup or for running vs. running comparison only?
Answer:
Startup and running configs are only compared with each other. The mask only works for host configurations of the running configuration.
Additional Information:
For more information on Device Family Comparison Masks, see:

https://docops.ca.com/ca-spectrum/10-1-to-10-1-2/en/managing-network/network-configuration-manager/global-synchronization-task#GlobalSynchronizationTask-ViewReferenceandRunningConfigurationDifferences

The Comparison Mask is a list of regular expressions that conceal device configuration content during a comparison with a historical configuration.
Any line in the device configuration file that matches a regular expression in the Comparison Mask is ignored during comparisons of configuration files. 
Network Configuration Manager provides a list of predefined masks that are displayed in the window next to Comparison Mask.