DCR display name not updated to hostname

Answered Question
Apr 10th, 2008
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Using CS 3.1.1 if I display total devices discovered, or reachable devices I see the hostname under the system name header. If I display devices updated to DCR I see IP addresses under the host name header. Also I don't see hostnames in device management. I can't locate a hostname using the advanced search.


Under discovery settings I have Preferred DCR display name: Hostname and Update DCR Display name: Yes


It is possible I changed those settings after the first discovery, but there have been other discoveries with those settings. Is there a way to update the DCR without too much pain?

Correct Answer by Martin Ermel about 9 years 2 weeks ago

My understanding of this:

Discovery does not necessarily resolve the System Name. With CS 3.1.1 you can get a list of the devices being discoverd by going to CS > Device and Credential > Device Discovery, then clicking on the number behind 'Total devices discovered'. The list that opens has an important column 'First Found by Module'. If 'CDP'is listed here - as it is in your case - the disco process gets the value for 'System Name' from the CDP Mib of a device. So there is no name resolution involved until now -regardless what you have configured for nameresolution in LMS.

The devices are NOT yet in DCR - this is just a list of what was discovered and by which module.

The type of nameresolution you have configured comes into play when device gets added to DCR. Then the configured mechanism is responsible for how to fill in the values for 'Display Name', 'Host Name' - and 'IP Address' as well! Because now it is determined which IP Address to use to communicate with the device (could be different then what is seen by CDP!) and how to resolve the Host Name and what to use as Display Name.

If you get the list of the devices IN DCR (or of those from Campus -Data Collection) then your settings for the name resolution have worked (... and you see what you have not expected ;-) )


Devices yet being in DCR have the value of 'System' under 'First Found by Module', so this is not a general 'First Found' but only from the point of view from the LAST disco process.


I hope this is right...

and explains why you have System Names in the Discovery List but not in the list of devices in DCR.

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Joe Clarke Thu, 04/10/2008 - 15:48
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Even if you changed the settings after the first Discovery, DCR should still be updated if new hostname information is found. Obtaining the hostname is based on your hostname resolution scheme. By default, Discovery will try and resolve the IP address by which it first discovers a device. It then resolves that hostname back to an IP (which it uses for its management IP address). Therefore, make sure that you can properly reverse-resolve your devices' IP addresses. The best way to do that is to use the NMSROOT/bin/resolver.pl script:


NMSROOT/bin/perl NMSROOT/bin/resolver.pl IP


Unfortunately, there is currently a bug in CS Discovery where even if you have DNS properly configured, IP addresses are not resolved to hostnames (see CSCso45657). The workaround is to add local hosts file entries for each device.


Your mismatched data in the various Discovery screens may be another bug. It would help to get some screenshots from you so that I have a clear picture of what's going on. First, pick one device in DCR, and get a screenshot of its properties. Then get screenshots from the total devices and devices updated to DCR screens.

alukes Fri, 04/11/2008 - 08:31
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Somehow discovery got the hostname, but not from DNS because I tried DNS on the Ciscoworks box and it doesn't resolve 10.16.1.1. Does discovery read the device config file for the hostname?



Joe Clarke Fri, 04/11/2008 - 09:43
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Ah, I see what you're seeing. The System Name it's showing you is the sysName from the device. However, since this sysName is not resolvable from DNS and/or you have not selected Resolve By SysName as your method of resolution, you will not see this name in DCR.


You will need to setup some kind of hostname/IP address resolution system (either DNS or hosts file) in order to get the hostnames to appear automatically in DCR.

Correct Answer
Martin Ermel Fri, 04/11/2008 - 09:51
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My understanding of this:

Discovery does not necessarily resolve the System Name. With CS 3.1.1 you can get a list of the devices being discoverd by going to CS > Device and Credential > Device Discovery, then clicking on the number behind 'Total devices discovered'. The list that opens has an important column 'First Found by Module'. If 'CDP'is listed here - as it is in your case - the disco process gets the value for 'System Name' from the CDP Mib of a device. So there is no name resolution involved until now -regardless what you have configured for nameresolution in LMS.

The devices are NOT yet in DCR - this is just a list of what was discovered and by which module.

The type of nameresolution you have configured comes into play when device gets added to DCR. Then the configured mechanism is responsible for how to fill in the values for 'Display Name', 'Host Name' - and 'IP Address' as well! Because now it is determined which IP Address to use to communicate with the device (could be different then what is seen by CDP!) and how to resolve the Host Name and what to use as Display Name.

If you get the list of the devices IN DCR (or of those from Campus -Data Collection) then your settings for the name resolution have worked (... and you see what you have not expected ;-) )


Devices yet being in DCR have the value of 'System' under 'First Found by Module', so this is not a general 'First Found' but only from the point of view from the LAST disco process.


I hope this is right...

and explains why you have System Names in the Discovery List but not in the list of devices in DCR.

alukes Fri, 04/11/2008 - 10:14
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You answered my next question which was going to be if Ciscoworks knows the hostname, why doesn't it just go ahead and enter it. I can see the dangers.


Is there is any way to automate discovering all of the 1070 devices that DNS needs to learn about?


Thanks to both of you for the help.

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