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When I configure "ntp server p1.ntp.net.nz" The router tries to resolve the name when it boots up but fails because the ADSL has not come up yet, So the router seams to deleted the host-name from running config.

This seams odd and can it be fixed?

I can enter the IP address of the host but that is not ideal.

Cisco IOS Software, 2800 Software (C2800NM-ADVSECURITYK9-M), Version 15.1(4)M1,

Thanks in advance,

David.

hertitu
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CNCdavid
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  • You could write an EEM script to add the ntp server after the ADSL comes up, but IMHO the more obvious solution would be to configure the ip address of the ntp server instead of the name, I don't see why that is not ideal... is the address of the server expected to change frequently? – hertitu Oct 02 '16 at 21:37
  • HI I am using the ip address and no i am not expecting to change often, It is not ideal because domain names are domain names and are designed to be used as such and the router has dns revolvers to use domain names in the way they are designed to be used. – CNCdavid Oct 04 '16 at 01:00
  • But the router does not seam to be functioning correctly. I will do the EEM script if I can't find any other way. I thought there may be a way to make the dns resolver retry instead of delete. Thanks David – CNCdavid Oct 04 '16 at 01:09
  • DNS names are really designed for applications. Network devices use IP addresses, and using DNS names is often not ideal in network devices. That's why anycast was invented. Also, the word is "seems", not "seams." – Ron Maupin Oct 06 '16 at 16:14

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This is fixed in IOS 15.1(4)M4 as part of the fix for bug CSCtw45592 . See also enhancement CSCsr86448 for a few caveats:

  • the router may be slow(er) to boot, as it will pause waiting for the DNS server
  • the DNS lookup is still only done at boot time so if the IP address of the NTP server changes, this change will only be picked up when the router reboots.
hertitu
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