In an L2TP voluntary tunneling scenario， the VPDN tunnel is terminated between：（）

单项选择题WhichoneofthefollowingisNOT asupportedIKEattribute？（）

A. PFS group.
B. Encryption algorithm.
C. Hashing Algorithm.
D. Authenticationmethod.
E. Lifetime duration.

单项选择题WithPGP，whichofthefollowingentitysignsausers’spublickey？（）

A. The sender of the message.
B. The receipient of the message.
C. The sender’s administrator who provides the sender with the PGP program.
D. A third party that belongs to what’s often known as "web of trust"， that can verify the relationship between the user and the key.
E. The vendor of the PGP program.

单项选择题WhenconfiguringamultipointGRE（mGRE）tunnelinterface，whichoneofthefollowingisNOTavalidconfigurationoption：（）

A. tunnel source
B. tunnel destination
C. tunnel key
D. ip address
E. tunnelvrf

多项选择题WhichofthefollowingstatementsthatdescribeDiffieHellmanKeyexchangearecorrect？（）

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）.

多项选择题SelectthetwocorrectstatementsfromthelistbelowthatdescribeDESand3DES：（）

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.