Which IPSEC protocol provides data integrity and authentication of packets?

• A. AH
• B. ESP
• C. IKE
• D. ipcomp

Answer: (A)

AH provides data integrity and authentication for IPsec-protected packets, ensuring the packet contents haven’t been altered in transit and that the packet originates from a trusted source. It authenticates the entire IP packet (header and payload) but does not encrypt the data, so confidentiality isn’t provided by AH. ESP, while capable of integrity and authentication, centers on delivering confidentiality through encryption and may include integrity checks, making it primarily a confidentiality mechanism. IKE is the key exchange protocol used to set up security associations, not to protect packet integrity directly, and ipcomp is simply for IP packet compression. So, for integrity and authentication without encryption, AH is the best fit.