What is the Server side credential cache?
The Server side credential cache is one of the two sets of credential caches for the ProxySG. The other cache credential is the client side credential cache. The "Credential Refresh" value is how long the ProxySG will keep a credential from the authentication server before verifying with the server again. Increasing the TTL for the credential refresh will reduce the load on the back end server. The back end server can be an LDAP server or server running the BCAAA agent.
The downside to increasing this TTL is a possible delay in a user account getting locked out or a delay in changes in group membership. The credential cache is only for BASIC authentication. This does not apply to NTLM/IWA unless it is a fall back credential.