We have several NetFlow and sFlow probes. For some subnets PTR resolution initially did not work. We have resolved the DNS issues and now from inside the OS were able to resolve the ip-to-host. However, those same ip's were not resolved/update inside the sensor. We have restarted the core services, cleared the PRTG cache (general "Clear Caches") , cleared the OS DNS resolver cache. Still the same - only the ip was shown for those hosts.
Then we did "Recalculate PRTG Graph Data Cache" - and that finally updated the resolution and brought in the host names.
So, I am guessing once the IP is in database, the PRTG is not trying to update the host name. Is there a way to force PRTG t update the ip-to-name record without expensive "Recalculate PRTG Graph Data Cache"? Also, if this is the case, i am wandering what happens for dynamic PTR records - how PRTG will update it once the PTR record changes? Please help us to understand the flow.