When configuring Pathfinder (the component used by Cortex XDR/XSIAM to perform host insights and remote analysis on unmanaged or target network endpoints) to use Kerberos for authentication, it relies heavily on proper Active Directory and DNS environmental health.
Kerberos authentication inherently requires mutual authentication and relies on strict name-to-IP and IP-to-name resolution. When Pathfinder attempts to authenticate to an endpoint using Kerberos, it uses the target's IP address to look up its host identity. Therefore, a fully functional Reverse DNS zone containing accurate, up-to-date Reverse DNS records (PTR records) must be validated on the DNS server. If the pointer (PTR) record is missing, incorrect, or doesn't match the forward lookup (A record), Kerberos ticket validation will fail, and authentication will fallback or error out.