Which of the following statements pertaining to link encryption is FALSE?

A.
It encrypts all the data along a specific communication path.

B.
It provides protection against packet sniffers and eavesdroppers.

C.
Information stays encrypted from one end of its journey to the other.

D.
User information, header, trailers, addresses and routing data that are part of the packets are encrypted.

Explanation:
Link encryption encrypts all the data along a specific communication path, as in a satellite link, T3 line, or
telephone circuit. Not only is the user information encrypted, but the header, trailers, addresses, and routing
data that are part of the packets are also encrypted. The only traffic not encrypted in this technology is the data
link control messaging information, which includes instructions and parameters that the different link devices
use to synchronize communication methods. Link encryption provides protection against packet sniffers and
eavesdroppers.
Link encryption, which is sometimes called online encryption, is usually provided by service providers and is
incorporated into network protocols. All of the information is encrypted, and the packets must be decrypted at
each hop so the router, or other intermediate device, knows where to send the packet next. The router must
decrypt the header portion of the packet, read the routing and address information within the header, and then
re-encrypt it and send it on its way.
Incorrect Answers:
A: It is true that link encryption encrypts all the data along a specific communication path.
B: It is true that link encryption provides protection against packet sniffers and eavesdroppers.
C: It is true that user information, header, trailers, addresses and routing data that are part of the packets are
encrypted.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 845-846