In link encryption, each entity has keys in common with its two neighboring nodes in
the transmission chain.
Thus, a node receives the encrypted message from its predecessor, decrypts it, and then re-
encrypts it with a new key, common to the successor node. Obviously, this mode does not provide
protection if anyone of the nodes along the transmission path is compromised.
Encryption can be performed at different communication levels, each with different types of
protection and implications. Two general modes of encryption implementation are link encryption
and end-to-end encryption.
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.
In end-to-end encryption, the headers, addresses, routing, and trailer information are not
encrypted, enabling attackers to learn more about a captured packet and where it is headed.
Reference(s) used for this question:
Harris, Shon (2012-10-25). CISSP All-in-One Exam Guide, 6th Edition (pp. 845-846). McGraw-Hill.
And:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of
Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography (page 132).

This approach is necessary to ensure that all the information required for a log-on has been submitted and to avoid providing information that would aid a cracker in trying to gain unauthorized access to the workstation or network. If a log-on attempt fails, information as to which part of the requested log-on information was incorrect should not be supplied to the user.
Answer "Provide a Help mechanism that provides log-on assistance" is incorrect since a Help utility would provide help to a cracker trying to gain unauthorized access to the network.
For answer "Place no limits on the time allotted for log-on or on the number of unsuccessful log-on attempts", maximum and minimum time limits should be placed on the log-on process. Also, the log-on process should limit the number of unsuccessful log-on attempts and temporarily suspend the log-on capability if that number is exceeded. One approach is to progressively increase the time interval allowed between unsuccessful log-on attempts.
Answer "Not provide information on the previous successful log-on and on previous unsuccessful log-on attempts" is incorrect since providing such information will alert an authorized user if someone has been attempting to
gain unauthorized access to the network from the user's workstation.

Explanation/Reference:
Explanation:
The internal walls of your processing facility must be a floor to ceiling slab with a one-hour minimum fire rating. Any adjacent walls where records such as paper, media, etc. must have a two-hour minimum fire rating.
There are different regulations that exist for external walls from state to state.
Incorrect Answers:
A: Walls to adjacent rooms where records such as paper and media are stored should have a two-hour minimum fire rating, not a one-hour fire rating. Therefore, this answer is incorrect.
C: It is not necessary for all walls to have a two-hour minimum fire rating. Therefore, this answer is incorrect.
D: It is not necessary for the internal walls to have a two-hour fire rating and it is not necessary for walls to adjacent rooms where records such as paper and media are stored should have a three-hour minimum fire rating. Therefore, this answer is incorrect.