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How does Auto-Discovery determine if a device already exists?



If I run Auto-Discovery, it sometimes adds a device that already exists, for example after I change the autmatically created name to something more useful. How can I prevent this?

auto-discovery device prevent

Created on Apr 1, 2010 6:38:06 PM

3 Replies

Accepted Answer



The name is irrelevant, important is the Host Name/IP entry.

auto discovery checks if an IP or if the reverse lookup host name already exists.

we will improve auto discovery in version 8 to prevent devices being created several times.

Created on Apr 8, 2010 5:15:12 AM by  Aurelio Lombardi [Paessler Support]



We have the same issue with auto discovery adding duplicate hosts to our installation. Our clients receive a DHCP address, however, the hostnames never change. Is it possible that the auto discovery is NOT using the fully qualified name for a host and therefore doesn't see the duplicate host record?

For example, we have a device called "workstation". The hostname is set to "workstation.domain.com". This host may get a new IP via DHCP every couple weeks. The next time the auto discovery runs on this subnet, is it possible it is checking PRTG for a hostname of "workstation" rather than "workstation.domain.com" and for this reason finds no match and is adding a new device? Or is it because the IP address changed on the device? We are using DNS names to probe rather than direct IPs because the IPs change.


Created on Aug 9, 2010 4:03:28 PM



Is the Name Resolution option set to Use IP addresses? Otherwise it would seem that the reverse DNS lookup generates a different name than that already extant for the device in case. If the latter holds true, the entry for IP address / DNS name should be different than the one used for the already configured device.

If the reverse DNS lookup doesn't return a FQDN - but at other times it does - these are also considered "different" devices.

Created on Aug 16, 2010 1:05:08 PM by  Patrick Hutter [Paessler Support] (7,225) 3 3

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