Today's another fun tale of pentest pwnage - specifically focused on cracking a hash type I'd never paid much attention to before: cached domain credentials. I also learned that you can at least partially protect against this type of hash being captured by checking out this article, which has you set the following setting in GPO:

• Under Computer Configuration > Policies > Windows Settings > Security Settings > Local Policies > Security Options set Interactive logon: Number of previous logons to cache to 0. Be careful, as you will have login problems if a domain controller is not immediately accessible!

In regards to defending against secretsdump, this article I found this article to be super interesting.