topic Re: Update DNS in ISE really this hard/bad? in Network Access Control

Update DNS in ISE really this hard/bad?

Dustin Anderson — Mon, 09 Jun 2025 16:58:06 GMT

OK, I'm on 3.3 patch 4 and we need to change the DNS IPs. We currently have 2 and when I tried to add one, it says it needs to reboot, so I said no so I could remove the 2, then add the new second. Problem is when you say no it does not save your change.

So, from what I can see is I have to:

1 Add new DNS as 3rd

2 Reboot

3 remove 2 old DNS

4 reboot

5 add 2nd new DNS since it's limited to 3 max.

6 reboot.

Is there really no way to replace or overwrite the current command so I only have to reboot once?

Re: Update DNS in ISE really this hard/bad?

adamscottmaster2013 — Mon, 09 Jun 2025 18:09:40 GMT

@Dustin Anderson: Yes, you can easily do it but it requires to open a TAC case with Cisco:

1- Open a TAC case with Cisco,

2- Get the engineer on the webex call,

3- have the TAC engineer root into the ISE,

4- The engineer will modify the /etc/resolv.conf file by removing the old DNS IPs and add new DNS IPs,

5- Reboot,

Since the ISE itself is Linux OS under the hood, I think it can be easily done.

Re: Update DNS in ISE really this hard/bad?

Dustin Anderson — Mon, 09 Jun 2025 19:08:38 GMT

ok, thanks. I'll try to work out a maint window for them to use.

Re: Update DNS in ISE really this hard/bad?

Arne Bier — Tue, 10 Jun 2025 00:42:06 GMT

It's not mandatory to reboot after EVERY DNS server change - I usually say "no" and save the reboot for the last change. It's badly implemented, but they do give you the option to NOT reboot - make use of that.

Re: Update DNS in ISE really this hard/bad?

Dustin Anderson — Wed, 11 Jun 2025 19:00:37 GMT

yeah, the issue I'm seeing in 3.3 is saying no does not save the change then. Otherwise that would be fine.

Re: Update DNS in ISE really this hard/bad?

Marcelo Morais — Thu, 26 Jun 2025 03:28:09 GMT

Hi @Dustin Anderson ,

yes, please take a look at: ISE - What we need to know about DNS Server, special attention to the " ... Note 1: the reset-config command ... "

Hope this helps !!!

Re: Update DNS in ISE really this hard/bad?

Dustin Anderson — Thu, 26 Jun 2025 13:51:36 GMT

Interesting way to do it in one shot. I'll keep it in mind, but hopefully we don't change the IPs again. I just did the 3 reboots after hours.

Re: Update DNS in ISE really this hard/bad?

Marcelo Morais — Thu, 26 Jun 2025 14:47:47 GMT

@Dustin Anderson ,

glad to be of a help !!!

Note: now you have another way to solve your issue, in case you need it in the future. : )