QUESTION 21

Which two protocols does the internet layer in the TCP/IP model encapsulate? (Choose two.)
TCP / IP模型中的因特层封装了哪两个协议？（选择两个）
A.   ICMP
B.   TCP
C.   ARP
D.   DNS
E.   SMTP

Correct Answer: AC
解析：ICMP和ARP工作在网络层，TCP工作在传输层，DNS和SMTP工作在应用层。  

 

 

QUESTION 22

Which command must you use to verify hostname-to-IP-address mapping information?
您必须使用哪条命令来验证主机名到IP地址的映射信息？
A.   show mac-address-table
B.   show sessions
C.   show arp
D.   show hosts

Correct Answer: D
解析：A选项命令可以查看到mac地址表，B选项命令可以查看到会话和连接用户信息，C选项命令可以查看到arp解析条目，D选项命令可以看到主机名和IP地址的映射关系。

 

 

 

 

 

QUESTION 23

Which two VLAN IDs indicate a default VLAN? (Choose two.)
哪两个VLAN ID表示默认VLAN？（选择两个）
A.   0
B.   1
C. 1005
D. 1006
E. 4096

  Correct Answer: BC
解析：vlan 1是默认的vlan，1005是为FDDI和令牌环网络提供的，也是默认的vlan。

 

 

QUESTION 24

According to security best practices, which two actions must you take to protect an unused switch port? (Choose two.)
符合安全的最佳做法，您必须采取以下哪两项措施来保护未使用的交换机端口？（选择两个）
A.   Administratively shutdown the port
B.   Configure the port as an access port on a VLAN other than VLAN 1.
C.   Enable CDP.
D.   Configure the port to automatically come online.
E.   Configure the port as a trunk port.

Correct Answer: AB
解析：管理性的关闭未使用的端口；将这些端口配置为除了vlan 1 外的其他vlan，并将端口设置为access模式。

 

 

 

 

QUESTION 25

Which two statements correctly describe distance-vector routing protocols? (Choose two)
哪两个语句正确描述了距离矢量路由协议？（选择两个）
A.   they specify the next hop toward the destination subnet
B.   they require quick network convergence to support normal operations
C.   they generate a complete topology of the network
D.   they update other devices on the network when one device detects a topogy chage
E.   they use a variety of metrics to identify the distance to a destination network.

  Correct Answer: AD
解析：距离：到达目标网络的度量值；矢量：去往目标网段的出接口/方向。A选项：指定达到目标网络的下一跳就是矢量（方向/出接口），D选项：使用各种指标来确定到目标网络的距离，就是度量值。

 

 

 

 

QUESTION 26

In which three ways is an IPv6 header simpler than an IPv4 header? (Choose three.)
IPv6头部在哪三个方面比IPv4头部更简单？（选择三个）
A.   Unlike IPv4 headers, IPv6 headers have a fixed length.
B.   IPv6 uses an extension header instead of the IPv4 Fragmentation field.
C.   IPv6 headers eliminate the IPv4 Checksum field.
D.   IPv6 headers use the Fragment Offset field in place of the IPv4 Fragmentation field.
E.   IPv6 headers use a smaller Option field size than IPv4 headers.
F.    IPv6 headers use a 4-bit TTL field, and IPv4 headers use an 8-bit TTL field.

  Correct Answer: ABC
解析：IPv4是变长报头，IPv6是定长报头；IPv4数据可能会分片，IPv6使用扩展头部，不需要分片；IPv6取消了头部校验和。

 

 

 

 

QUESTION 27

Which two statements about exterior routing protocols are true? (Choose two.)
关于外部路由协议的哪两种说法是正确的？（选择两个）
A.   BGP is the current standard exterior routing protocol
B.   Most modern networking supports both EGP and BGP for external routing
C.   They determine the optimal path between autonomous systems
D.   Most modern network routers support both EGP and EIGRP for external routing
E.   They determine the optimal path within an autonomous system

  Correct Answer: AC
解析：BGP是标准的外部网关协议，可以和同AS、不同AS的网络器建立邻居关系，决定了自治系统之间的最佳路径。

 

 

 

 

QUESTION 28

Which two actions must you take to correctly configure PPPoE on a client? (Choose two.)
要在客户端上正确配置PPPoE，您必须采取哪两种操作？（选择两个）
A.   Define a dialer interface.
B.   Create a BBA group and link it to the dialer interface.
C.   Define a virtual template interface.
D.   Create a dialer pool and bind it to the physical interface.
E.   Create a dialer pool and bind it to the virtual template.

  Correct Answer: AD
解析：创建一个拨号接口；创建拨号池，将其关联到物理接口上。

 

 

 

 

QUESTION 29

Which two statements about MPLS are true? (Choose two.)
关于MPLS的哪两个陈述是正确的？（选择两个）
A.   It uses labels to separate and forward customer traffic.
B.   It tags customer traffic using 802.1q
C.   It can carry mutiple protocols, including IPv4 and IPv6.
D.   It encapsulates all traffic in an IPv4 header
E.   It provides automatic authentication.

Correct Answer: AC
解析：MPLS通过标签去分隔和转发客户的流量；支持多种协议，其中包括IPv4和IPv6。

 

 

 

 

QUESTION 30

Frame flooding can occur in which circumstance?
哪种情况下会发生帧泛洪？
A.   The destination IP address is missing from the route table.
B.   The source IP address is missing from the route table.
C.   The destination MAC address is missing from the CAM table.
D.   The source MAC address is missing from the CAM table.

  Correct Answer: C
解析：交换机接收到数据帧，要依据CAM表中的映射条目进行转发，如果目的设备mac地址不在CAM表中，则会泛洪该数据帧。