Sybex CEH Certified Ethical Hacker Version 8 Study Guide

418 Appendix A ■ Answers to Review Questions
14. D. A true mesh topology creates a natural amount of redundancy due to the number of connections
used to establish connectivity.
15. C. Because each switchport is its own collision domain, only nodes that reside on the same
switchport will be seen during a scan.
16. D. Proxies act as intermediaries between internal host computers and the outside world.
17. 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.
18. C. Intrusion prevention systems (IPSs) play an active role in preventing further suspicious
activity after it is detected.
19. 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.
20. D. Packet filtering firewalls operate at layer 7 of the OSI model and thus filter traffic at a
highly granular level.
Chapter 3: Cryptography
1. A. Symmetric cryptography is also known as shared key cryptography.
2. D. A certification authority is responsible for issuing and managing digital certificates as
well as keys.
3. B. Asymmetric encryption uses two separate keys and is referred to as public key cryptography.
Symmetric algorithms use only one key that is used by both the sender and receiver.
4. 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.
5. C. A message digest is a product of a hashing algorithm, which may also be called a message
digest function.
6. 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.
7. 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.
8. A. The number of keys increases dramatically with more and more parties using symmetric
encryption hence it does not scale well.