Explanation/Reference:
PPTP operates at the data link layer (layer 2) of the OSI model and uses native PPP authentication and encryption services. Designed for individual client to server connections, it enables only a single point-to- point connection per session.
PPTP - Point-to-Point Tunneling Protocol - extends the Point to Point Protocol (PPP) standard for traditional dial-up networking. PPTP is best suited for the remote access applications of VPNs, but it also supports LAN internetworking.
PPTP operates at Layer 2 of the OSI model.
Using PPTP
PPTP packages data within PPP packets, then encapsulates the PPP packets within IP packets (datagrams) for transmission through an Internet-based VPN tunnel. PPTP supports data encryption and compression of these packets. PPTP also uses a form of General Routing Encapsulation (GRE) to get data to and from its final destination.
Reference(s) used for this question:
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 95).
and
http://compnetworking.about.com/od/vpn/l/aa030103a.htm
and
http://technet.microsoft.com/en-us/library/cc768084.aspx

Absolute/Direct
+------+-----+--------------------------------------+ | load | reg | address | +------+-----+--------------------------------------+
(Effective address = address as given in instruction)
This requires space in an instruction for quite a large address. It is often available on CISC machines which have variable-length instructions, such as x86.
Some RISC machines have a special Load Upper Literal instruction which places a 16-bit
constant in the top half of a register. An OR literal instruction can be used to insert a 16-bit
constant in the lower half of that register, so that a full 32-bit address can then be used via
the register-indirect addressing mode, which itself is provided as "base-plus-offset" with an
offset of 0.
http://en.wikipedia.org/wiki/Addressing_mode (Very good coverage of the subject)
also see:
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, page 186.
also see:
http://www.comsci.us/ic/notes/am.html

Explanation/Reference:
The Pretty Good Privacy (PGP) email encryption system was developed by Phil Zimmerman. For encrypting messages, it actually uses AES with up to 256-bit keys, CAST, TripleDES, IDEA and Twofish.
RSA is also used in PGP, but only for symmetric key exchange and for digital signatures, but not for encryption.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography (pages 154, 169).
More info on PGP can be found on their site at http://www.pgp.com/display.php?pageID=29.

Section: Network and Telecommunications
Explanation/Reference:
A spoofing attack is when an attempt is made to gain access to a computer system by posing as an authorized user or system. Spamming refers to sending out or posting junk advertising and unsolicited mail. A smurf attack is a type of denial-of-service attack using PING and a spoofed address. Sniffing refers to observing packets passing on a network.
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
77).