What is the main purpose of split-horizon operation for DNS servers?

• A. To enhance security by providing different DNS responses based on the source of the request.
• B. To speed up DNS resolution.
• C. To allow dynamic updates.
• D. To balance load.

Answer: (A)

Split-horizon DNS is all about serving different DNS answers depending on where the query comes from. The idea is to keep internal network details hidden from the outside while still giving internal users fast, correct access to internal resources. In practice, a single domain can resolve to private IP addresses for internal clients and to public addresses for external clients, or return entirely different records based on the query origin. This separation helps protect the internal topology and sensitive names while still providing appropriate resolution to each network segment. It’s not primarily about speeding up lookups, enabling dynamic updates, or balancing load, though it can incidentally influence those effects in some setups.