chapitre7

 

 

CCNA Security Chapter 7 Exam Answers

    1.    What is the focus of cryptanalysis?

·         hiding secret codes

·         developing secret codes

·         breaking encrypted codes

·         implementing encrypted codes

    2.    How many bits does the Data Encryption Standard (DES) use for data encryption?

·         40 bits

·         56 bits

·         64 bits

·         72 bits

    3.    Which statement describes the Software-Optimized Encryption Algorithm (SEAL)?

·         SEAL is a stream cipher.

·         It uses a 112-bit encryption key.

·         It is an example of an asymmetric algorithm.

·         It requires more CPU resources than software-based AES does.

    4.    Which encryption algorithm is an asymmetric algorithm?

·         DH

·         SEAL

·         3DES

·         AES

    5.    An online retailer needs a service to support the nonrepudiation of the transaction. Which component is used for this service?

·         the private key of the retailer

·         the unique shared secret known only by the retailer and the customer

·         the public key of the retailer

·         the digital signatures

    6.    In which situation is an asymmetric key algorithm used?

·         Two Cisco routers authenticate each other with CHAP.

·         User data is transmitted across the network after a VPN is established.

·         An office manager encrypts confidential files before saving them to a removable device.

·         A network administrator connects to a Cisco router with SSH.

    7.    What is the purpose of a nonrepudiation service in secure communications?

·         to ensure that encrypted secure communications cannot be decoded

·         to confirm the identity of the recipient of the communications

·         to provide the highest encryption level possible

·         to ensure that the source of the communications is confirmed

    8.    Which objective of secure communications is achieved by encrypting data?

·         integrity

·         authentication

·         confidentiality

·         availability

    9.    Why is the 3DES algorithm often preferred over the AES algorithm?

·         3DES is more trusted because it has been proven secure for a longer period than AES.

·         AES is more expensive to implement than 3DES.

·         3DES performs better in high-throughput, low-latency environments than AES.

·         Major networking equipment vendors such as Cisco have not yet adopted AES.

    10.    What is the most common use of the Diffie-Helman algorithm in communications security?

·         to create password hashes for secure authentication

·         to provide routing protocol authentication between routers

·         to encrypt data for secure e-commerce communications

·         to secure the exchange of keys used to encrypt data

    11.    Which type of encryption algorithm uses public and private keys to provide authentication, integrity, and confidentiality?

·         symmetric

·         shared secret

·         IPsec

·         asymmetric

    12.    How do modern cryptographers defend against brute-force attacks?

·         Use statistical analysis to eliminate the most common encryption keys.

·         Use a keyspace large enough that it takes too much money and too much time to conduct a successfulattack.

·         Use an algorithm that requires the attacker to have both ciphertext and plaintext to conduct a successful attack.

·         Use frequency analysis to ensure that the most popular letters used in the language are not used in the cipher message.

   13.    Which encryption protocol provides network layer confidentiality?

·         IPsec protocol suite

·         Transport Layer Security

·         Secure Hash Algorithm 1

·         Secure Sockets Layer

·         Keyed MD5

·         Message Digest 5

    14.    Refer to the exhibit. Which encryption algorithm is described in the exhibit?

·         RC4

·         AES

·         3DES

·         DES

·         SEAL

    15.    Which statement describes asymmetric encryption algorithms?

·         They have key lengths ranging from 80 to 256 bits.

·         They include DES, 3DES, and AES.

·         They are also called shared-secret key algorithms.

·         They are relatively slow because they are based on difficult computational algorithms.

    16.    Which two non-secret numbers are initially agreed upon when the Diffie-Hellman algorithm is used? (Choose two.)

·         binomial coefficient

·         generator

·         elliptic curve invariant

·         prime modulus

·         topological index

·         pseudorandom nome

    17.    In what situation would an asymmetric algorithm most likely be used?

·         logging onto a computer

·         making an online purchase

·         uploading a networking book chapter using FTP

·         transferring a large stream of data between two corporate locations

    18.    Why is asymmetric algorithm key management simpler than symmetric algorithm key management?

·         It uses fewer bits.

·         Only one key is used.

·         Two public keys are used for the key exchange.

·         One of the keys can be made public.

    19.    What is the purpose of code signing?

·         source identity secrecy

·         integrity of source .EXE files

·         reliable transfer of data

·         data encryption

    20.    Which algorithm can ensure data confidentiality?

·         MD5

·         PKI

·         RSA

·         AES

    21.    What is the purpose of a digital certificate?

·         It guarantees that a website has not been hacked.

·         It authenticates a website and establishes a secure connection to exchange confidential data.

·         It provides proof that data has a traditional signature attached.

·         It ensures that the person who is gaining access to a network device is authorized.

     22.    Fill in the blank.
A shared secret is a symmetric key used in a encryption algorithm.