A stream cipher is a type of symmetric encryption algorithm that operates on continuous streams of plain text and is appropriate for hardware-based encryption.
Stream ciphers can be designed to be exceptionally fast, much faster than any block cipher. A stream cipher generates what is called a keystream (a sequence of bits used as a key).
Stream ciphers can be viewed as approximating the action of a proven unbreakable cipher, the one-time pad (OTP), sometimes known as the Vernam cipher. A one-time pad uses a keystream of completely random digits. The keystream is combined with the plaintext digits one at a time to form the ciphertext. This system was proved to be secure by Claude Shannon in 1949. However, the keystream must be (at least) the same length as the plaintext, and generated completely at random. This makes the system very cumbersome to implement in practice, and as a result the one-time pad has not been widely used, except for the most critical applications.
A stream cipher makes use of a much smaller and more convenient key - 128 bits, for
example. Based on this key, it generates a pseudorandom keystream which can be
combined with the plaintext digits in a similar fashion to the one-time pad. However, this
comes at a cost: because the keystream is now pseudorandom, and not truly random, the
proof of security associated with the one-time pad no longer holds: it is quite possible for a
stream cipher to be completely insecure if it is not implemented properly as we have seen
with the Wired Equivalent Privacy (WEP) protocol.
Encryption is accomplished by combining the keystream with the plaintext, usually with the
bitwise XOR operation.
Source: DUPUIS, Clement, CISSP Open Study Guide on domain 5, cryptography, April
1999.
More details can be obtained on Stream Ciphers in RSA Security's FAQ on Stream
Ciphers.

DES works with 64 bit blocks of text using a 64 bit key (with 8 bits used for parity, so the effective key length is 56 bits).
Some people are getting the Key Size and the Block Size mixed up. The block size is usually a specific length. For example DES uses block size of 64 bits which results in 64
bits of encrypted data for each block. AES uses a block size of 128 bits, the block size on
AES can only be 128 as per the published standard FIPS-197.
A DES key consists of 64 binary digits ("0"s or "1"s) of which 56 bits are randomly
generated and used directly by the algorithm. The other 8 bits, which are not used by the
algorithm, may be used for error detection. The 8 error detecting bits are set to make the
parity of each 8-bit byte of the key odd, i.e., there is an odd number of "1"s in each 8-bit
byte1. Authorized users of encrypted computer data must have the key that was used to
encipher the data in order to decrypt it.
IN CONTRAST WITH AES
The input and output for the AES algorithm each consist of sequences of 128 bits (digits
with values of 0 or 1). These sequences will sometimes be referred to as blocks and the
number of bits they contain will be referred to as their length. The Cipher Key for the AES
algorithm is a sequence of 128, 192 or 256 bits. Other input, output and Cipher Key lengths
are not permitted by this standard.
The Advanced Encryption Standard (AES) specifies the Rijndael algorithm, a symmetric
block cipher that can process data blocks of 128 bits, using cipher keys with lengths of 128,
192, and 256 bits. Rijndael was designed to handle additional block sizes and key lengths,
however they are not adopted in the AES standard.
The AES algorithm may be used with the three different key lengths indicated above, and
therefore these different "flavors" may be referred to as "AES-128", "AES-192", and "AES-
256".
The other answers are not correct because:
"64 bits of data input results in 56 bits of encrypted output" is incorrect because while DES
does work with 64 bit block input, it results in 64 bit blocks of encrypted output.
"128 bit key with 8 bits used for parity" is incorrect because DES does not ever use a 128
bit key.
"56 bits of data input results in 56 bits of encrypted output" is incorrect because DES
always works with 64 bit blocks of input/output, not 56 bits.
Reference(s) used for this question:
Official ISC2 Guide to the CISSP CBK, Second Edition, page: 336-343
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf

The answer above is the correct answer because it is FALSE. Rijndael does
not support multiples of 64 bits but multiples of 32 bits in the range of 128 bits to 256 bits.
Key length could be 128, 160, 192, 224, and 256.
Both block length and key length can be extended very easily to multiples of 32 bits. For a
total combination of 25 different block and key size that are possible.
The Rijndael Cipher
Rijndael is a block cipher, designed by Joan Daemen and Vincent Rijmen as a candidate
algorithm for the Advanced Encryption Standard (AES) in the United States of America.
The cipher has a variable block length and key length.
Rijndael can be implemented very efficiently on a wide range of processors and in
hardware.
The design of Rijndael was strongly influenced by the design of the block cipher Square.
The Advanced Encryption Standard (AES)
The Advanced Encryption Standard (AES) keys are defined to be either 128, 192, or 256
bits in accordance with the requirements of the AES.
The number of rounds, or iterations of the main algorithm, can vary from 10 to 14 within the Advanced Encryption Standard (AES) and is dependent on the block size and key length. 128 bits keys uses 10 rounds or encryptions, 192 bits keys uses 12 rounds of encryption, and 256 bits keys uses 14 rounds of encryption.
The low number of rounds has been one of the main criticisms of Rijndael, but if this ever becomes a problem the number of rounds can easily be increased at little extra cost performance wise by increasing the block size and key length.
Range of key and block lengths in Rijndael and AES Rijndael and AES differ only in the range of supported values for the block length and cipher key length.
For Rijndael, the block length and the key length can be independently specified to any multiple of 32 bits, with a minimum of 128 bits, and a maximum of 256 bits. The support for block and key lengths 160 and 224 bits was introduced in Joan Daemen and Vincent Rijmen, AES submission document on Rijndael, Version 2, September 1999 available at http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf
AES fixes the block length to 128 bits, and supports key lengths of 128, 192 or 256 bits only.
Reference used for this question:
The Rijndael Page and http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf and FIPS PUB 197, Advanced Encryption Standard (AES), National Institute of Standards and Technology, U.S. Department of Commerce, November 2001.

Explanation/Reference:
IEEE 802.3 specifies the standard for Ethernet and uses CSMA/CD, not token-passing.
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
104).

Explanation/Reference:
Actually the term "remanence" comes from electromagnetism, the study of the electromagnetics.
Originally referred to (and still does in that field of study) the magnetic flux that remains in a magnetic circuit after an applied magnetomotive force has been removed. Absolutely no way a candidate will see anywhere near that much detail on any similar CISSP question, but having read this, a candidate won't be likely to forget it either.
It is becoming increasingly commonplace for people to buy used computer equipment, such as a hard drive, or router, and find information on the device left there by the previous owner; information they thought had been deleted. This is a classic example of data remanence: the remains of partial or even the entire data set of digital information. Normally, this refers to the data that remain on media after they are written over or degaussed. Data remanence is most common in storage systems but can also occur in memory.
Specialized hardware devices known as degaussers can be used to erase data saved to magnetic media.
The measure of the amount of energy needed to reduce the magnetic field on the media to zero is known as coercivity.
It is important to make sure that the coercivity of the degausser is of sufficient strength to meet object reuse requirements when erasing data. If a degausser is used with insufficient coercivity, then a remanence of the data will exist. Remanence is the measure of the existing magnetic field on the media; it is the residue that remains after an object is degaussed or written over.
Data is still recoverable even when the remanence is small. While data remanence exists, there is no assurance of safe object reuse.
Reference(s) used for this question:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 4207-4210). Auerbach Publications. Kindle Edition.
and
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 19694-19699). Auerbach Publications. Kindle Edition.