Symmetric cryptography ciphers are generally fast and hard to break. So speed is one of the key advantage of Symmetric ciphers and NOT a disadvantage.
Symmetric Ciphers uses simple encryption steps such as XOR, substitution, permutation, shifting columns, shifting rows, etc... Such steps does not required a large amount of processing power compare to the complex mathematical problem used within Asymmetric
Ciphers.
Some of the weaknesses of Symmetric Ciphers are:
The lack of automated key distribution. Usually an Asymmetric cipher would be use to protect the symmetric key if it needs to be communicated to another entity securely over a public network. In the good old day this was done manually where it was distributed using the Floppy Net sometimes called the Sneaker Net (you run to someone's office to give them the key).
As far as the total number of keys are required to communicate securely between a large group of users, it does not scale very well. 10 users would require 45 keys for them to communicate securely with each other. If you have 1000 users then you would need almost half a million key to communicate secure. On Asymmetric ciphers there is only 2000 keys required for 1000 users. The formula to calculate the total number of keys required for a group of users who wishes to communicate securely with each others using Symmetric encryption is Total Number of Users (N) * Total Number of users minus one Divided by 2 or
N (N-1)/2
Symmetric Ciphers are limited when it comes to security services, they cannot provide all of the security services provided by Asymmetric ciphers. Symmetric ciphers provides mostly confidentiality but can also provide integrity and authentication if a Message
Authentication Code (MAC) is used and could also provide user authentication if Kerberos is used for example. Symmetric Ciphers cannot provide Digital Signature and Non-
Repudiation.
Reference used for theis question:
WALLHOFF, John, CBK#5 Cryptography (CISSP Study Guide), April 2002 (page 2).

The component that is included in the Global System for Mobile Communications (GSM) security framework is symmetric key cryptography. GSM is a standard for mobile communication that is widely used around the world. GSM provides various services and features, such as voice, data, text, multimedia, roaming, or emergency calls. GSM also provides various security mechanisms and functions, such as authentication, encryption, or integrity. The GSM security framework is a set of specifications or protocols that define the security architecture, components, and procedures of the GSM system. The GSM security framework includes various components, such as the Subscriber Identity Module (SIM), the Authentication Center (AuC), the Equipment Identity Register (EIR), or the ciphering algorithms. The component that is included in the GSM security framework is symmetric key cryptography, which is a type of cryptography that uses the same key or a pair of keys that are mathematically related for both encryption and decryption of data or information.
Symmetric key cryptography is used in the GSM security framework for various purposes, such as encrypting the communication between the mobile station and the base station, generating the authentication and ciphering keys, or deriving the session keys. Symmetric key cryptography can help to ensure the confidentiality, integrity, and authenticity of the data or information in the GSM system, as well as to protect the data or information from various security threats or attacks, such as eavesdropping, interception, or modification. Public-Key Infrastructure (PKI), digital signatures, or biometric authentication are not the components that are included in the GSM security framework, as they are either more related to the asymmetric key cryptography, which is a type of cryptography that uses different keys for encryption and decryption of data or information, or to the identity verification, which is a process of confirming the identity of a person or entity. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 6: Secure Network Architecture and Securing Network Components, page 388; CISSP Official (ISC)2 Practice Tests, Third Edition, Domain 4: Communication and Network Security, Question 4.11, page 188.

Explanation/Reference:
Explanation:
With a screened subnet, two firewalls are used to create a DMZ.
Incorrect Answers:
B: The three legged model is just one way of implementing a DMZ. A DMZ can be implemented in different ways.
C: A place to attract hackers is called a honeypot, not a DMZ.
D: A bastion host is not a DMZ. It is a computer that is fully exposed to attack.
References:
Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 646

The correct answer is "Private addresses can easily be routed globally" Private addresses are not easily routable; hence the reason for using NAT.