The OSI/ISO Data Link layer is made up of two sub-layers; (1) the Media Access Control layer refers downward to lower layer hardware functions and (2) the Logical Link Control refers upward to higher layer software functions. Other choices are distracters.
Source: ROTHKE, Ben, CISSP CBK Review presentation on domain 2, August 1999.

Explanation/Reference:
Simple Mail Transfer Protocol (SMTP) is a host-to-host email protocol. An SMTP server accepts email messages from other systems and stores them for the addressees. Stored email can be read in various ways. Users with interactive accounts on the email server machine can read the email using local email applications. Users on other systems can download their email via email clients using POP or IMAP email retrieval protocols. Sometimes mail can also be read through a web-based interface (using HTTP or HTTPS). MIME is a standard defining the format of e-mail messages, as stated in RFC2045.
Source: GUTTMAN, Barbara & BAGWILL, Robert, NIST Special Publication 800-xx, Internet Security Policy: A Technical Guide, Draft Version, May 25, 2000 (pages 91-92).

A denial-of-service attack is aimed at depriving an organization of its resources. They are typically intentional attacks targeted against a specific system or network.

Section: Network and Telecommunications
Explanation/Reference:
TACACS+ is a proprietary Cisco enhancement to TACACS and is more robust than RADIUS. PAP is not a remote access authentication system but a remote node security protocol.
Source: 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
122).

The main concern when recovering after a disaster is data, telecomm and IS
facilities. Other services, in descending priority order are: IS operations, IS support
services, market structure, marketing/public relations, customer service & systems support,
market regulation/surveillance, listing, application development, accounting services,
facilities, human resources, facilities security, legal and Office of the Secretary, national
sales.
Source: BARNES, James C. & ROTHSTEIN, Philip J., A Guide to Business Continuity
Planning, John Wiley & Sons, 2001 (page 129).