ATM is an example of a fast packet-switching network that can be used for
either data, voice or video, but packets are of fixed size.
Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-
Hill/Osborne, 2002, chapter 7: Telecommunications and Network Security (page 455).

This layer of the DoD Model is also sometimes called Transport in some books but the proper name is Host-to-Host as per the RFC document.
The host-to-host layer provides for reliable end-to-end communications, ensures the data's error-free delivery, handles the data's packet sequencing, and maintains the data's integrity.
It is comparable to the transport layer of the OSI model.
Reference(s) used for this question:
http://en.wikipedia.org/wiki/Internet_protocol_suite and http://technet.microsoft.com/en-us/library/cc786900%28v=ws.10%29.aspx and KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 85).

Explanation/Reference:
From the published (ISC)2 goals for the Certified Information Systems Security Professional candidate:
The CISSP candidate should be familiar to communications and network security as it relates to voice, data, multimedia, and facsimile transmissions in terms of local area, wide area, and remote access.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 57.

Although a loss of skilled workers knowledge would cause the company a great loss, it is not identified as a specific loss criteria. It would fall under one of the three other criteria listed as distracters. Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, chapter 9: Disaster Recovery and Business continuity (page 598).

Explanation/Reference:
Banners at the log-on time should be used to notify external users of any monitoring that is being conducted. A good banner will give you a better legal stand and also makes it obvious the user was warned about who should access the system and if it is an unauthorized user then he is fully aware of trespassing.
This is a tricky question, the keyword in the question is External user.
There are two possible answers based on how the question is presented, this question could either apply to internal users or ANY anonymous user.
Internal users should always have a written agreement first, then logon banners serve as a constant reminder.
Anonymous users, such as those logging into a web site, ftp server or even a mail server; their only notification system is the use of a logon banner.
References used for this question:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 50.
and
Shon Harris, CISSP All-in-one, 5th edition, pg 873