A. A DH key exchange is an algorithm that utilizes asymmetric cryptographic keys.
B. The DH key exchange is used to establish a shared secret over an insecure medium during an IPSec phase 1 exchange.
C. The DH exchange is susceptible to man-in-the-middle attacks.
D. The DH exchange is used to authenticate the peer device duringan IPSec phase 1 exchange.
E.A DH exchange provides Perfect Forward Secrecy （PFS）.

A. 3DES is muchmore secure than DES.
B. Both DES and 3DES are stream ciphers.
C. DES uses 64 bitkeys， although the effective key lengthis only 56bits.
D. The decryption operation for both DES and 3DES is the same as the encryption operation.
E. DES can only be used for encryption， whereas 3DES can also be used for authentication.

A. The RADIUSVendor Specific Attribute type is decimal 26.
B. A radius server that does not understandthevendor-specific information sent by a clientmust reject the authentication request.
C. A vendor can freely choose theVendor-ID it wants to use when implementing Vendor Specific Attributes as long as the same Vendor-ID is used on all of its products.
D. Vendor Specific AttributeMUST include the Length field.
E. In Cisco’s Vendor Specific Attribute implementation， vendor-ID of 1 is commonly referred to as Cisco AV（Attribute Value） pairs.
F. Vendor Specific Attributes use a RADIUS attribute type between 127 and 255.

A. Access-reject
B. Access-response
C. Access-challenge
D. Access-reply
E. Access-accept

A.Prevents DoS from legimate， non-hostile end systems
B.Prevents disruption of "special services"， such as Mobile IP
C.Defeats DoS Attacks which employ IPSource Address Spoofing
D.Restricts directed broadcasts at the ingress router
E.Allows DHCP or BOOTP packets to reach the relay agents asappropriate