Cisco Certified Network Associate (CCNA) Practice Exam

Which of the following is a characteristic of Authentication Header (AH)?

1. It encrypts data in transit

2. It sends data in cleartext

3. It is used exclusively for VPN connections

4. It cannot be used in conjunction with other protocols

The correct answer is: It sends data in cleartext

The correct characteristic of Authentication Header (AH) is that it sends data in cleartext. AH is part of the IPsec protocol suite and is primarily focused on providing integrity, authentication, and non-repudiation for IP packets. It achieves this by including a cryptographic checksum within the header, ensuring that the data has not been tampered with during transmission. While AH provides these important security features, it does not provide encryption for the data itself, meaning that the original data remains visible in cleartext. Users can see the payload without the need for decryption, which distinguishes it from other protocols that focus on confidentiality through encryption. In contrast, the other characteristics are not accurate for AH. It does not encrypt data in transit, as its function is strictly to authenticate rather than to secure the content of the data being sent. AH is also not exclusively used for VPN connections; it can be utilized in various networking scenarios where authentication of packets is necessary. Lastly, AH can be used in conjunction with other protocols, including ESP (Encapsulating Security Payload), which can provide encryption, thereby enhancing the security scope beyond what AH offers alone.