CompTIA Network+ Practice Test

What is added to the packet header by the Authentication Header (AH) protocol?

1. A hash of the packet and a shared key

2. A new IP address

3. An encryption key

4. A trailer for packet validation

The correct answer is: A hash of the packet and a shared key

The correct choice involves the addition of a hash of the packet and a shared key to the packet header by the Authentication Header (AH) protocol. This is an important aspect of AH, which is part of the IPsec suite used to provide data integrity and authentication for IP packets. When AH is applied, it computes a hash value over certain fields of the packet, including the packet header and payload, using a shared key known only to the sender and recipient. This hash is then added to the packet header, allowing the receiver to verify that the packet has not been altered in transit. By performing a hash operation, AH ensures that any modifications to the packet would result in a different hash value, alerting the recipient to potential tampering. The other options do not accurately represent what AH adds to the packet header. A new IP address is not modified or added by AH; rather, AH simply focuses on securing the existing packet data. An encryption key is related to confidentiality protocols, like the Encapsulating Security Payload (ESP), rather than the authentication focus of AH. Lastly, a trailer for packet validation is more associated with encryption protocols, which may place additional data at the end of the packet rather than in the header. Thus, the process