Questions about acquireTokenByClientCredential caching

We are using acquireTokenByClientCredential to get an app-to-app token. We tried using the same user multiple times and it seemed to cache since I didn't see any extra calls going out to MS. But I did have a couple questions:

1. What is the TTL of this cached token?
2. Is there any documentation that explains how the cache for this works? From documentation found here I found this section:

"Since this is a “client credentials flow”, this uses the application token cache. This method takes care of verifying the application token cache before sending a request to the security token service (STS)."

But that's as much as I could find on it