Which IPsec feature ensures that data cannot be altered in transit?

• A. Data replication
• B. Data integrity
• C. Data compression
• D. Data censorship

Answer: (B)

Data integrity is what protects against tampering in transit. In IPsec, integrity uses a message authentication code (MAC)—often via AH or ESP with authentication—to verify that the payload hasn’t been altered since it was created. If any bit or bytes change along the way, the MAC no longer matches the shared secret, and the receiver detects the tampering and discards the packet or raises an alert. This focus on detecting modifications distinguishes it from data replication, compression, or censorship, which do not by themselves guarantee that data hasn’t been altered en route. If you ever see IPsec described as providing authenticity and integrity, that’s the combined effect, but the core mechanism that prevents undetected changes is data integrity.