If ASL blocks anything, it will log that action. Just log into the ASL GUI, set the level to "1", and type in the IP address into the Event: box in the Security Events window.
If you want to find out if ASL has shunned, or firewalled off an IP address previously, just click on the ASL tab, then then select Blocking. Any IP address that ASL is blocking will be listed in that window.
If you have blacklisted an IP, then check the Blacklist window.
And if you are using the geoblocking features, check the Geoblocking window for the list of countries you have configured ASL to block.
If you are unable to log into the ASL web console, you can also check the ASL active response log. All shuns are logged by ASL. Please see this FAQ for further information:
Can I search for a domain to see if its been blocked?
Yes, just use the domain name instead of the IP.