Discovery: How to age out hosts that are no longer being scanned

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    BMC Discovery


    BMC Discovery 11.3


    BMC Discovery



    A customer asks if there is an option to age hosts that are no longer being scanned. The customer only scans IP addresses that are known to exist to decrease the time it takes to scan the network. As a result, obsolete IPs are not scanned and never age out. 





    Legacy ID:KA375834

    One possible way to age obsolete IPs without actually re-scanning them is to specify the IP in an exclude range, but leave it as part of the list of IPs to be scanned. When running the scan, Discovery will check if the IP is in an exclude list, and if so it will generate a "Skipped" Discovery Access. Discovery interprets this a scan failure and will thus decrement the age count of the Host. (The field age_count represents the number of consecutive successful (positive) or failed (negative) accesses for any endpoint.) When the age_count reaches the aging criteria specified in the Model Maintenance page, the Host will be eligible for aging out, and on the next scan it should be destroyed. 


    An alternative is to run a query to search for all devices with a Last Update Success older than a given date. For example, this following query searches for all Hosts with a Last Update Success older than September 1, 2019: 

    search Host where last_update_success < parseLocalTime('2019-9-1 00:00:00') show name, #InferredElement:Inference:Associate:DiscoveryAccess.endpoint as 'Scanned via', last_update_success as 'Last Update Success' 

    Then select the Hosts to be destroyed (or select ALL) and choose Actions > Destroy. 

    Please note that if Desktops were formerly discovered, and then "Discover desktop hosts" is set to NO, the desktop scans will then end as Skipped / Excluded, but the Desktops themselves will not age off. Defect DRUD1-19310 was created for this, and a fix is tentatively planned for the next major release after 11.3. 


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