FTP - Port 21
Telnet - Port 23
SMTP - Port 25
DNS - Port 53
The port numbers are divided into three ranges: the Well Known Ports, the Registered Ports, and
the Dynamic and/or Private Ports.
The Well Known Ports are those from 0 through 1023.
The Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535.
Reference : http://www.iana.org/assignments/port-numbers
For the purpose of the exam you DO NOT need to know all of the 65,535 ports but you must know the one that are very commonly used.

Explanation/Reference:
Explanation:
DES is a symmetric block encryption algorithm. When 64-bit blocks of plaintext go in, 64-bit blocks of ciphertext come out. It is also a symmetric algorithm, meaning the same key is used for encryption and decryption. It uses a 64-bit key: 56 bits make up the true key, and 8 bits are used for parity.
When the DES algorithm is applied to data, it divides the message into blocks and operates on them one at a time. The blocks are put through 16 rounds of transposition and substitution functions. The order and type of transposition and substitution functions depend on the value of the key used with the algorithm. The result is 64-bit blocks of ciphertext Incorrect Answers:
A: When 64-bit blocks of plaintext go in, 64-bit blocks of encrypted data come out.
B: DES uses a 64-bit key (not 128-bit): 56 bits make up the true key, and 8 bits are used for parity.
D: DES uses 64-bit blocks, not 56-bit.
References:
Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 801

Section: Security Architecture and Engineering
Explanation:
Only the person having correspondent private key can encrypt the plaintext decrypted (verified) by the public key, so proper identification of the endpoints are maintained.