418 Appendix A ■ Answers to Review Questions
- D. A true mesh topology creates a natural amount of redundancy due to the number of con-
nections used to establish connectivity. - C. Because each switchport is its own collision domain, only nodes that reside on the same
switchport will be seen during a scan. - D. Proxies act as intermediaries between internal host computers and the outside world.
- D. Network Address Translation (NAT) is a technology that funnels all internal traffic
through a single public connection. NAT is implemented for both cost savings and network
security. - C. Intrusion prevention systems (IPSs) play an active role in preventing further suspicious
activity after it is detected. - D. Simple Mail Transfer Protocol (SMTP) operates on port 25 and is used for outgoing mail
traffic. In this scenario, the IDS SMTP configuration needs to be updated. - D. Packet filtering firewalls operate at layer 7 of the OSI model and thus filter traffic at a
highly granular level.
Chapter 3: Cryptography
- A. Symmetric cryptography is also known as shared key cryptography.
- D. A certification authority is responsible for issuing and managing digital certificates as
well as keys. - B. Asymmetric encryption uses two separate keys and is referred to as public key cryptogra-
phy. Symmetric algorithms use only one key that is used by both the sender and receiver. - C. Hashing is referred to as a cipher or algorithm or even a cryptosystem, but it can be
uniquely referred to as a nonreversible mechanism for verifying the integrity of data.
Remember that hashing doesn’t enforce confidentiality. - C. A message digest is a product of a hashing algorithm, which may also be called a mes-
sage digest function. - C. A public and private key are mathematically related keys, but they are not identical. In
symmetric systems only one key is used at a time. - B. A public key is not necessarily stored on the local system, but a private key will always
be present if the user is enrolled. - A. The number of keys increases dramatically with more and more parties using symmetric
encryption hence it does not scale well.
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