DNS Security Extensions (DNSSEC) is the best security measure to mitigate redirection attacks within the resolution protocol, as it ensures that the information provided by the name servers has not been tampered with by cryptographically signing the data. This ensures the authenticity and integrity of the data, substantially reducing the risk of such attacks. Frequent cache clearing can help eliminate corrupted cache entries but does not safeguard against the initial attack. Implementing a web proxy does not protect the integrity of the resolution data and is therefore not as effective. Closing unused ports may enhance perimeter security but has no direct effect on the security of the resolution protocol itself.