What is the purpose of using TSIG in DNS?

The purpose of using TSIG, or Transaction Signature, in DNS primarily revolves around cryptographic authentication, which is critical for maintaining security within DNS communications. TSIG provides a way to authenticate DNS messages between servers, ensuring that the messages exchanged are actually from the anticipated source and have not been tampered with during transit. This authentication helps to prevent spoofing attacks, where an unauthorized entity might send false DNS information to redirect traffic or cause disruption.

In the context of DNS, spoofing can lead to various attacks such as cache poisoning, which can compromise the integrity of the DNS cache by inserting fraudulent records. By incorporating TSIG into the DNS protocol, DNS servers can verify the authenticity of the messages they receive and respond to, significantly enhancing the security posture of DNS operations.

The other choices do not capture the primary function of TSIG effectively. While speeding up DNS requests or adding more records might be beneficial in certain scenarios, they are not direct functions of TSIG. Similarly, recording all DNS transactions is not a purpose of TSIG; rather, TSIG focuses on authenticating and verifying specific transactions to safeguard against malicious activities.