Quick post: I had a HA pair of ISE boxes in a lab the other day have the certificates that I made with a Windows Certificate Authority expire the other day and I ran into some odd behavior. To be clear, in this scenario, the certificates had a valid chain of trust, but it was past its expiration date.

I logged in after realizing this and had odd behavior, node-A could not read node-Bs certificates. Both nodes said they were no longer on domain, even though the domain disagreed and I logged in with domain credentials that were recently changed. Then when I went to make a Certificate Signing Request (CSR), I was able to make it, but when I went to download it I got a generic message of “Cannot connect to node-a”. At the same time all these issues were going on, under “Node Status” on the dashboard, both nodes were sharing health data.

In the end, ISE gets weird when the cert date has expired. I generated a new self signed cert for node-A. Then deleted the expired certs because the system didnt want me to make a CSR for the same thing it thought it had a cert for already. This allowed me to then properly make a CSR and export it. That gave me “ciscoisenodea.pem”, I brought that over to my setup Windows CA, and with a admin command prompt ran certreq -submit -attrib "CertificateTemplate:WebServer" ciscoisenodea.pem . Saved that to my local desktop, and went into ISE to Bind it to the CSR. Node-A then rebooted. All of a sudden things like the domain pairing, started showing they were working again. Then the second node, I did the same process, and all of a sudden everything was happy again. Note: make sure you have a your admin backup password, one of the nodes DID refuse to talk to AD and I had to use that, while the other one said it wasn’t on the domain, but did work…

Hope this helps someone out there!