Last Updated on November 1, 2019 by Admin
Implementing Network Security ( Version 2.0) – CCNAS Chapter 7 Exam Online
CCNAS – Chapter 7 Exam
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CCNAS – Chapter 7 Exam
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Question 1 of 22
1. Question
1 pointsWhat is the focus of cryptanalysis?Correct
Incorrect
Cryptology is the science of making and breaking secret codes. There are two separate disciplines in cryptology, cryptography and cryptanalysis. Cryptography is the development and use of codes. Cryptanalysis is the breaking of those secret (encrypted) codes.
Hint
Cryptology is the science of making and breaking secret codes. There are two separate disciplines in cryptology, cryptography and cryptanalysis. Cryptography is the development and use of codes. Cryptanalysis is the breaking of those secret (encrypted) codes. 
Question 2 of 22
2. Question
1 pointsHow many bits does the Data Encryption Standard (DES) use for data encryption?Correct
Incorrect
DES uses a fixed length key. The key is 64bits long, but only 56 bits are used for encryption. The remaining 8 bits are used for parity. A DES encryption key is always 56 bits long. When DES is used with a weaker encryption of a 40bit key, the encryption key is 40 secret bits and 16 known bits, which make the key length 56 bits.
Hint
DES uses a fixed length key. The key is 64bits long, but only 56 bits are used for encryption. The remaining 8 bits are used for parity. A DES encryption key is always 56 bits long. When DES is used with a weaker encryption of a 40bit key, the encryption key is 40 secret bits and 16 known bits, which make the key length 56 bits. 
Question 3 of 22
3. Question
1 pointsWhich statement describes the SoftwareOptimized Encryption Algorithm (SEAL)?Correct
Incorrect
SEAL is a stream cipher that uses a 160bit encryption key. It is a symmetric encryption algorithm that has a lower impact on the CPU resources compared to other softwarebased algorithms, such as softwarebased DES, 3DES, and AES.
Hint
SEAL is a stream cipher that uses a 160bit encryption key. It is a symmetric encryption algorithm that has a lower impact on the CPU resources compared to other softwarebased algorithms, such as softwarebased DES, 3DES, and AES. 
Question 4 of 22
4. Question
1 pointsWhich encryption algorithm is an asymmetric algorithm?Correct
Incorrect
DH is an asymmetric algorithm. AES, 3DES, and SEAL are all symmetric algorithms.
Hint
DH is an asymmetric algorithm. AES, 3DES, and SEAL are all symmetric algorithms. 
Question 5 of 22
5. Question
1 pointsAn online retailer needs a service to support the nonrepudiation of the transaction. Which component is used for this service?Correct
Incorrect
Digital signatures, generated by hash function, can provide the service for nonrepudiation of the transaction. Both public and private keys are used to encrypt data during the transaction. Shared secrets between the retailer and customers are not used.
Hint
Digital signatures, generated by hash function, can provide the service for nonrepudiation of the transaction. Both public and private keys are used to encrypt data during the transaction. Shared secrets between the retailer and customers are not used. 
Question 6 of 22
6. Question
1 pointsIn which situation is an asymmetric key algorithm used?Correct
Incorrect
The SSH protocol uses an asymmetric key algorithm to authenticate users and encrypt data transmitted. The SSH server generates a pair of public/private keys for the connections. Encrypting files before saving them to a storage device uses a symmetric key algorithm because the same key is used to encrypt and decrypt files. The router authentication with CHAP uses a symmetric key algorithm. The key is preconfigured by the network administrator. A VPN may use both an asymmetric key and a symmetric encryption algorithm. For example in an IPSec VPN implementation, the data transmission uses a shared secret (generated with an asymmetric key algorithm) with a symmetric encryption algorithm used for performance.
Hint
The SSH protocol uses an asymmetric key algorithm to authenticate users and encrypt data transmitted. The SSH server generates a pair of public/private keys for the connections. Encrypting files before saving them to a storage device uses a symmetric key algorithm because the same key is used to encrypt and decrypt files. The router authentication with CHAP uses a symmetric key algorithm. The key is preconfigured by the network administrator. A VPN may use both an asymmetric key and a symmetric encryption algorithm. For example in an IPSec VPN implementation, the data transmission uses a shared secret (generated with an asymmetric key algorithm) with a symmetric encryption algorithm used for performance. 
Question 7 of 22
7. Question
1 pointsWhat is the purpose of a nonrepudiation service in secure communications?Correct
Incorrect
Nonrepudiation uses the unique characteristics of the sender of a message to confirm that the reputed sender is in fact the actual sender.
Hint
Nonrepudiation uses the unique characteristics of the sender of a message to confirm that the reputed sender is in fact the actual sender. 
Question 8 of 22
8. Question
1 pointsWhich objective of secure communications is achieved by encrypting data?Correct
Incorrect
When data is encrypted, it is scrambled to keep the data private and confidential so that only authorized recipients can read the message. A hash function is another way of providing confidentiality.
Hint
When data is encrypted, it is scrambled to keep the data private and confidential so that only authorized recipients can read the message. A hash function is another way of providing confidentiality. 
Question 9 of 22
9. Question
1 pointsWhy is the 3DES algorithm often preferred over the AES algorithm?Correct
Incorrect
Despite its advantages, AES is a relatively young algorithm. An important rule of cryptography is that a mature algorithm is always more trusted. 3DES is therefore a more trusted choice in terms of strength, because it has been tested and analyzed for 35 years. AES can be used in highthroughput, lowlatency environments, especially when 3DES cannot handle the throughput or latency requirements. AES is available in a number of Cisco VPN devices as an encryption transform.
Hint
Despite its advantages, AES is a relatively young algorithm. An important rule of cryptography is that a mature algorithm is always more trusted. 3DES is therefore a more trusted choice in terms of strength, because it has been tested and analyzed for 35 years. AES can be used in highthroughput, lowlatency environments, especially when 3DES cannot handle the throughput or latency requirements. AES is available in a number of Cisco VPN devices as an encryption transform. 
Question 10 of 22
10. Question
1 pointsWhat is the most common use of the DiffieHelman algorithm in communications security?Correct
Incorrect
DiffieHelman is not an encryption mechanism and is not typically used to encrypt data. Instead, it is a method to securely exchange the keys used to encrypt the data.
Hint
DiffieHelman is not an encryption mechanism and is not typically used to encrypt data. Instead, it is a method to securely exchange the keys used to encrypt the data. 
Question 11 of 22
11. Question
1 pointsWhich type of encryption algorithm uses public and private keys to provide authentication, integrity, and confidentiality?Correct
Incorrect
An asymmetric encryption algorithm uses two keys, namely a public key and a private key. A symmetric encryption algorithm uses an identical key for both encryption and decryption. A shared secret is an example of using symmetric algorithm.
Hint
An asymmetric encryption algorithm uses two keys, namely a public key and a private key. A symmetric encryption algorithm uses an identical key for both encryption and decryption. A shared secret is an example of using symmetric algorithm. 
Question 12 of 22
12. Question
1 pointsHow do modern cryptographers defend against bruteforce attacks?Correct
Incorrect
In a bruteforce attack, an attacker tries every possible key with the decryption algorithm knowing that eventually one of them will work. To defend against the bruteforce attacks, modern cryptographers have as an objective to have a keyspace (a set of all possible keys) large enough so that it takes too much money and too much time to accomplish a bruteforce attack. A security policy requiring passwords to be changed in a predefined interval further defend against the bruteforce attacks. The idea is that passwords will have been changed before an attacker exhausts the keyspace.
Hint
In a bruteforce attack, an attacker tries every possible key with the decryption algorithm knowing that eventually one of them will work. To defend against the bruteforce attacks, modern cryptographers have as an objective to have a keyspace (a set of all possible keys) large enough so that it takes too much money and too much time to accomplish a bruteforce attack. A security policy requiring passwords to be changed in a predefined interval further defend against the bruteforce attacks. The idea is that passwords will have been changed before an attacker exhausts the keyspace. 
Question 13 of 22
13. Question
1 pointsWhich encryption protocol provides network layer confidentiality?Correct
Incorrect
Cryptographic encryption can provide confidentiality at several layers of the OSI model. For example, network layer protocols, such as the IPsec protocol suite, provide network layer confidentiality. Secure Sockets Layer (SSL) or Transport Layer Security (TLS), provide session layer confidentiality. MD5, Keyed MD5, and Secure Hash Algorithm 1 are examples of hash functions. They provide data integrity but not data confidentiality.
Hint
Cryptographic encryption can provide confidentiality at several layers of the OSI model. For example, network layer protocols, such as the IPsec protocol suite, provide network layer confidentiality. Secure Sockets Layer (SSL) or Transport Layer Security (TLS), provide session layer confidentiality. MD5, Keyed MD5, and Secure Hash Algorithm 1 are examples of hash functions. They provide data integrity but not data confidentiality. 
Question 14 of 22
14. Question
1 pointsRefer to the exhibit. Which encryption algorithm is described in the exhibit?Correct
Incorrect
3DES is a good choice to protect data because it has an algorithm that is very trusted and has security strength.
Hint
3DES is a good choice to protect data because it has an algorithm that is very trusted and has security strength. 
Question 15 of 22
15. Question
1 pointsWhich statement describes asymmetric encryption algorithms?Correct
Incorrect
DES, 3DES, and AES are examples of symmetric encryption algorithms (also known as shared secret key algorithms). The usual key length for symmetric algorithms is 80256 bits. Asymmetric algorithms are relatively slow because they are based on difficult computational algorithms.
Hint
DES, 3DES, and AES are examples of symmetric encryption algorithms (also known as shared secret key algorithms). The usual key length for symmetric algorithms is 80256 bits. Asymmetric algorithms are relatively slow because they are based on difficult computational algorithms. 
Question 16 of 22
16. Question
2 pointsWhich two nonsecret numbers are initially agreed upon when the DiffieHellman algorithm is used? (Choose two.)Correct
Incorrect
DH is a mathematical algorithm that allows two hosts to generate an identical shared secret on both systems without having communicated before. To start a DH exchange, both hosts must agree on two nonsecret numbers. The first number is a base number, also called the generator. The second number is a prime number that is used as the modulus. These numbers are usually public and are chosen from a table of known values.
Hint
DH is a mathematical algorithm that allows two hosts to generate an identical shared secret on both systems without having communicated before. To start a DH exchange, both hosts must agree on two nonsecret numbers. The first number is a base number, also called the generator. The second number is a prime number that is used as the modulus. These numbers are usually public and are chosen from a table of known values. 
Question 17 of 22
17. Question
1 pointsIn what situation would an asymmetric algorithm most likely be used?Correct
Incorrect
Asymmetric algorithms are slow, so they are commonly used in lowvolume transactions such as making online purchases or logging into a financial website.
Hint
Asymmetric algorithms are slow, so they are commonly used in lowvolume transactions such as making online purchases or logging into a financial website. 
Question 18 of 22
18. Question
1 pointsWhy is asymmetric algorithm key management simpler than symmetric algorithm key management?Correct
Incorrect
Asymmetric algorithms use two keys, a public and a private key. Key management is simpler because one of the keys can be made public.
Hint
Asymmetric algorithms use two keys, a public and a private key. Key management is simpler because one of the keys can be made public. 
Question 19 of 22
19. Question
1 pointsWhat is the purpose of code signing?Correct
Incorrect
Code signing is used to verify the integrity of executable files downloaded from a vendor website. Code signing uses digital certificates to authenticate and verify the identity of a website.
Hint
Code signing is used to verify the integrity of executable files downloaded from a vendor website. Code signing uses digital certificates to authenticate and verify the identity of a website. 
Question 20 of 22
20. Question
1 pointsWhich algorithm can ensure data confidentiality?Correct
Incorrect
Data confidentiality is ensured through symmetric encryption algorithms, including DES, 3DES, and AES.
Hint
Data confidentiality is ensured through symmetric encryption algorithms, including DES, 3DES, and AES. 
Question 21 of 22
21. Question
1 pointsWhat is the purpose of a digital certificate?Correct
Incorrect
Digital signatures commonly use digital certificates that are used to verify the identity of the originator in order to authenticate a vendor website and establish an encrypted connection to exchange confidential data. One such example is when a person logs into a financial institution from a web browser.
Hint
Digital signatures commonly use digital certificates that are used to verify the identity of the originator in order to authenticate a vendor website and establish an encrypted connection to exchange confidential data. One such example is when a person logs into a financial institution from a web browser. 
Question 22 of 22
22. Question
1 pointsWhat type of encryption algorithm uses the same key to encrypt and decrypt data?Correct
Incorrect
Symmetric encryption algorithms use the same key (also called shared secret) to encrypt and decrypt the data. In contrast, asymmetric encryption algorithms (also called publickey) use a pair of keys, one for encryption and another for decryption.
Hint
Symmetric encryption algorithms use the same key (also called shared secret) to encrypt and decrypt the data. In contrast, asymmetric encryption algorithms (also called publickey) use a pair of keys, one for encryption and another for decryption.