Information
Running a Split-Horizon DNS architecture refers to running authoritative DNS servers and services for external DNS queries separate from the internal authoritative DNS servers, which answer all queries originating from within the organization. The external servers are configured to provide only a limited amount of information for the services needed for communication with external clients and services. Typically, the information published in the externally available DNS is the minimal needed for the Internet services such as mail, web and gateway systems such as VPNs. The separate internal DNS service typically provides a more rich information set typically needed by internal clients.
Rationale:
The two goals of Split-Horizon are to:
1. Minimize the amount and type of externally available information.
2. Physical and logical separation of external and internal DNS services.
Separating the external and internal DNS servers in this manner adheres to a defense-indepth approach that limits the potential damage and impact should the external name server be compromised, since it does not service internal clients, nor does it have information on the internal systems and services.
NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.
Solution
Implement Split-Horizon Architecture to separate external and internal DNS services.