ICND2-Chap17

Question 1

VPN Encryption Algorithms: Data Encryption Standard (DES)

Answer 1

Key Length 56 bits; Older and less secure than the other options listed here.

Question 2

VPN Encryption Algorithms: Triple DEX (3DES)

Answer 2

56 bits x 3; Applies three different 56-bit DES keys in succession; improving the encryption strength versus DES.

Question 3

VPN Encryption Algorithms: Advanced Encryption Standard (AES)

Answer 3

128 and 256 bits; Considered the current best practice; with strong encryption and less computation than 3DES.

Question 4

Diffie-Hellman Option: DH-1 Key Length

Answer 4

768-bit

Question 5

Diffie-Hellman Option: DH-2 Key Length

Answer 5

1024-bit

Question 6

Diffie-Hellman Option: DH-5 Key Length

Answer 6

1536-bit

Question 7

Intranet VPN

Answer 7

Connects all the computers at two sites of the same organization; typically using one VPN device at each site

Question 8

Extranet VPN

Answer 8

Connects all the computers at two sites of different but partnering organizations; typically using one VPN device at each state

Question 9

Access VPN

Answer 9

Connects individual Internet users to the enterprise network

Question 10

IPsec Message integrity option: HMAC-MD5

Answer 10

HMAC-MD5 uses a 128-bit shared key; generating a 128-bit hash value

Question 11

IPsec Message integrity option: HMAC-SHA

Answer 11

HMAC-Secure Hash Algorithm defines different key sizes (for example; SHA-1 [160]; SHA-256 [256]; and SHA-512 [512]) to support different encryption key sizes. Considered better than MD5 but with more compute-time required.

Question 12

IPsec Authentication option: Pre-Shared Keys

Answer 12

Both VPN devices must be preconfigured with the same secret key.

Question 13

Ipsec Authentication option: Digital signatures

Answer 13

Also called Rivest; Shamir and Adelman (RSA) signatures. The sender encrypts a value with its private key; the receiver decrypts with the sender’s public key and compares with the value listed by the sender in the header.

Question 14

Functions Supported by IPsec Encapsulating Security Payload (ESP)

Answer 14

Authentication (weak); Message integrity; Encryption; Antireplay

Question 15

Functions Supported by IPsec IP Authentication Header (AH)

Answer 15

Authentication (strong); Message integrity