A. the buffer overflow attack indicates that an attacker uses defects of memory operations of the software system and runs attack codes with high operation rights.

B. the buffer overflow attack is irrelevant to the OS vulnerabilities and architecture.

C. the buffer overflow attack is the most common attack of the software system.

D. the buffer overflow attack is an application-layer attack.

A. Virtual link can solve the problem that backbone areas are logically non-contiguous.

B. A virtual link can be established between any two ABRs, but the two routers must have interface that are connected to the same non backbone are

C. routers must have interfaces that are connected to the same

D. A virtual link unnecessarily belongs to the backbone area, Instead, which area It belongs to depends on the actual topology.

E. A virtual link belongs to Area 0.

A. After NAPT translation all packets are from the same IP address for external users

B. ln No-PAT mode only the transport layer protocol port number can be converted

C. ln NAPT mode only the network layer protocol address can be converted

D. ln No-PAT mode the network layer protocol address can be converted

A. True

B. FALSE

A. To ensure that sensitive management information will not be intercepted

B. To prevent or reduce external network attacks and harm

C. To ensure secure access to key services

D. To achieve secure user access control