For more information regarding the security incident at F5, the actions we are taking to address it, and our ongoing efforts to protect our customers, click here.

Forum Discussion

Nikoolayy1's avatar
Aug 26, 2025

DNS/GTM health monitor big3d timeout because of alias config

Hello Everyone,

 

I was testing some experimental config for DNS/GTM where the health monitor does not monitor the pool members but a specific IP address configured in the "alias" and it does not work as the error says bigd timeouts to report the state.

 

For LTM http/https health monitors the "alias" option works but not for gtm/dns. I think I discovered a bug as this is rare use case to not monitor the pool members themselves.

 

I have changed the ip to 1.1.1.1 just for the picture screenshot 😄

 

Also in the logs after gtm and big3d is enabled I see the logs below and too bad that F5 DNS does not have monitor debug like LTM to just enable a debug for a monitor and not the entire box.

 

-----

Will not probe x.x.x.x:80 ( in DC /Common/niki-dc because will be done by other GTM (<unknown>:<unknown>)

Unable to identify which gtm server represents the local device

 

 

 

 

1 Reply

  • ok resolved the issue by looking at the logs as did not add the F5 gtm/dns itself as a server in the GSLB config as to be selected for monitoring and now the "alias" ip address is monitored even without adding it as a server object. Someone has to read the logs 🐸