Switching, Routing, and Wireless Essentials

1. 当启用DHCP 的客户端PC 启动时，客户端PC 是否使用广播消息与DHCP 服务器通信？（选择两项。）

DHCPDISCOVERDHCPACKDHCPOFFERDHCPREQUESTDHCPNAK

说明： 启用DHCP 的客户端和DHCP 服务器之间的所有DHCP 消息都使用广播消息，直到发送DHCPACK 消息。在启用DHCP 的客户端之间发送的所有DHCP 消息都只是DHCPDISCOVER 和DHCPREQUEST 消息。当客户端首次获得租约时，客户端和DHCP 服务器使用广播消息。

DHCP 客户端和DHCP 服务器之间的DHCP 消息是广播消息，直到DHCP 客户端发送DHCPACK 消息。 DHCPDISCOVER 和DHCPREQUEST 消息是启用DHCP 的客户端发送的唯一消息。当DHCP客户端第一次申请租约时，DHCP客户端和DHCP服务器之间的所有DHCP报文都使用广播报文。

2. 管理员发出命令：

路由器(配置)# 接口g0/1

路由器(config-if)#ip地址dhcp

管理者想要实现什么目标？

配置路由器以充当DHCPv4 服务器配置路由器以从DHCPv4 服务器获取IP 参数配置路由器以充当中继代理配置路由器以解决IP 地址冲突

3. 当客户端向DHCP 服务器请求初始地址租用时，为什么DHCPREQUEST 消息以广播形式发送？

客户端尚不知道发送优惠的DHCP 服务器的IP 地址。 DHCP 服务器可能位于不同的子网上，因此请求必须以广播形式发送。由于客户端尚未分配MAC 地址，因此无法在第2 层发送单播消息。客户端可能已收到来自多个服务器的报价，并且广播用于隐式拒绝那些其他报价。

说明： 在客户端和服务器之间的初始DHCP 交换期间，客户端广播DHCPDISCOVER 消息以查找DHCP 服务器。客户端可以配置为通过发送DHCPOFFER 消息来响应此请求。 DHCP请求消息。以广播形式发送此消息，以便发送该优惠的其他DHCP 服务器知道该优惠已被拒绝，并可以将相应的地址放回池中。

4. 哪个DHCP IPv4 消息包含以下信息？

目的地地址： 255.255.255.255

客户端IPv4 地址： 0.0.0.0

默认网关地址： 0.0.0.0

子网掩码： 0.0.0.0

DHCPACKDHCPDISCOVERDHCPOFFERDHCPREQUEST

5.按以下顺序排列选项：

客户端发起消息寻找DHCP 服务器 DHCPDISCOVER DHCP 服务器响应客户端的初始请求 DHCPOFFER 客户端接受DHCP 服务器提供的IP 地址 DHCPREQUEST DHCP 服务器确认租约已被接受 DHCPACK

6. 哪些协议可以自动分配网络上的IP 地址？（选择两项。）

DHCDNSSMB536780

说明：DNS 使用端口53 将URL 转换为IP 地址。 SMB 提供对文件和打印机的共享访问并使用端口445。 HTTP 是用于Web 浏览器和服务器之间通信的协议。

7. 如果将PC1 配置为从DHCP 服务器获取动态IP 地址，则PC1 将关闭两周并尝试声明可用的IP 地址。 IP 标头？

192.168.1.1192.168.1.255255.255.255.255192.168.1.8

说明： 当主机启动并配置动态IP 地址时，设备会尝试获取有效的IP 地址，因为DHCP 服务器地址未知（设计原因）。 IP 标头值为255.255.255.255，目标MAC 地址为FF:FF:FF:FF:FF:FF。

8. 当IPv4 主机收到来自DHCP 服务器的DHCPOFFER 消息时，它使用哪个消息来响应？

DHCPOFFERDHCPDISCOVERDHCPREQUESTDHCPACK

描述： 当客户端从服务器收到DHCPOFFER 时，它会发回DHCPREQUEST 广播消息。服务器收到DHCPREQUEST 消息后，以单播DHCPACK 消息进行响应。

9. 如果启用了到ISP 的链路，在路由器接口配置模式下发出哪个命令可以使接口自动从ISP 获取IPv4 地址？

服务dhcpip 地址dhcpip helper-addressip dhcp 池

描述：ip address dhcpinterface 配置命令将以太网接口配置为DHCP 客户端。发出service dhcpglobal 配置命令以在路由器上启用DHCPv4 服务器进程。 ip dhcp pool 命令为池创建一个名称。服务器可以分配给主机的地址数量。

10. 当IP地址租约到期时，DHCP客户端会发送什么类型的消息？

DHCPDISCOVER 单播消息DHCPREQUEST 广播消息DHCPREQUEST 单播消息DHCPDISCOVER 广播消息

描述： 当DHCP 客户端IP 地址的租用时间到期时，将直接向最初提供IPv4 地址的DHCPv4 服务器发送DHCPREQUEST 单播消息。

11. 主机PC 尝试通过DHCP 租用地址。服务器发送什么消息让客户端知道它可以使用所提供的IP 信息？

DHCPDISCOVERDHCPOFFERDHCPREQUESTDHCPACKDHCPNACK

解释： 当主机使用DHCP 自动配置IP 地址时，通常会以广播形式发送两条消息：一条DHCPDISCOVER 消息和一条DHCPREQUEST 消息，并且所有DHCP 服务器都将收到使用DHCPOFFER 广播的这些消息。DHCPACK 和DHCPNACK 消息（视情况而定）。

12. Windows 计算机未从DHCP 服务器接收IPv4 地址的标志是什么？

计算机无法ping 通127.0.0.1。计算机接收以169.254 开头的IP 地址。 Windows 显示DHCP 超时消息。计算机无法ping 通同一网络上IP 地址在169.254.0.0/16 范围内的其他设备。

说明： 如果Windows PC 无法与IPv4 DHCP 服务器通信，计算机会自动分配169.254.0.0/16 范围内的IP 地址。同一网络上接收同一范围内的地址的其他设备是可以访问的。

13. 客户端发送哪个DHCPv4 消息来接受DHCP 服务器提供的IPv4 地址？

广播DHCPACK 广播DHCPREQUEST 单播DHCPACK 单播DHCPREQUEST

描述当：DHCP 客户端收到DHCPOFFER 消息时，它会发送广播DHCPREQUEST 消息，用于两个目的。首先是通知DHCP服务器接受offer并绑定IP地址。第二个通知其他响应的DHCP。通知您来自服务器的报价已被拒绝。

14. 一家小咖啡店为顾客提供免费无线网络连接。该网络包括连接到当地电话公司的无线路由器和DSL 调制解调器。通常使用哪些方法来配置与电话公司的连接？

将无线路由器的WAN 连接配置为DHCP 客户端。将无线路由器和DSL 调制解调器之间的连接配置为专用IP 网络。将DSL 调制解调器配置为DHCP 客户端，以从无线路由器获取公共IP 地址。放。 DSL 调制解调器充当电话公司的DHCP 客户端以及内部连接的DHCP 服务器。

描述：在SOHO 环境中，您的无线路由器通过DSL 或电缆调制解调器连接到ISP。通常，无线路由器和ISP 站点之间的IP 地址不受DSL 调制解调器管理。

15.公司使用DHCP来管理员工工作站的IP地址部署，在数据中心部署多个DHCP服务器，并使用DHCP中继代理来处理来自工作站的DHCP请求。哪两个UDP 端口用于转发DHCP 流量？（选择两项。）

2353676880

说明：DHCP 协议在两个UDP 端口上运行。 UDP 端口67 是DHCP 服务器的目的端口，DHCP 客户端使用UDP 端口68。

16. 以太网段上的客户端设备需要IP 地址才能在网络上进行通信。网络上配置并启用了IP 地址为192.168.1.1 的DHCP 服务器。客户端设备如何获取可用的IP地址？这个网络？

向默认网关地址发送DHCPACK 数据包。使用DHCP 服务器提供的IP 地址池中的静态配置的IP 地址。向物理地址FF-FF-FF-FF-FF-FF 发送DHCPDISCOVER 消息。向IP 地址255.255.255.255 发送DHCPREQUEST 数据包。

描述： 与IP 寻址类似，还有一个用于广播目的的特殊MAC 地址。 FF-FF-FF-FF-FF-FF 如果DHCP 客户端需要发送DHCP Discover 消息来查找DHCP 服务器，则客户端使用此地址苹果。这是因为它不知道DHCP 服务器的IP 和MAC 地址。

17. 将Cisco路由器配置为中继代理有什么好处？

为多种UDP服务提供中继服务，减少DHCP服务器的响应时间。这允许DHCPDISCOVER 消息无需修改即可转发。

说明： ip helper-address 命令默认转发以下八种UDP 服务：

端口37: 小时

端口49: TACACS

端口53: DNS

端口67:DHCP/BOOTP 客户端

端口68: DHCP/BOOTP 服务器

端口69:TFTP

端口137: NetBIOS 名称服务

端口138: NetBIOS 数据报服务

18. 关于DHCP 的操作，以下哪一项是正确的？

当配置为使用DHCP 引导的设备时，客户端会广播DHCPDISCOVER 消息来识别网络上可用的DHCP 服务器。客户端必须等到租约到期才能发送。

another DHCPREQUEST message.​If the client receives several DHCPOFFER messages from different servers, it sends a unicast DHCPREQUEST message to the server from which it chooses to obtain the IP information.The DHCPDISCOVER message contains the IP address and subnet mask to be assigned, the IP address of the DNS server, and the IP address of the default gateway.​
Explanation: The client broadcasts a DHCPDISCOVER message to identify any available DHCP servers on the network. A DHCP server replies with a DHCPOFFER message. This message offers to the client a lease that contains such information as the IP address and subnet mask to be assigned, the IP address of the DNS server, and the IP address of the default gateway. After the client receives the lease, the received information must be renewed through another DHCPREQUEST message prior to the lease expiration.

19. Order the DHCP message types as they would occur between a DHCP client and a DHCP server.

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network.
The DHCPOFFER message is used by a server to offer a lease to a client. The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.
The DHCPACK message is used by a server to finalize a successful lease with a client.
The DHCPNAK message is used when an offered lease is no longer valid.

20. A network administrator configures a router to send RA messages with M flag as 0 and O flag as 1. Which statement describes the effect of this configuration when a PC tries to configure its IPv6 address?

It should contact a DHCPv6 server for the prefix, the prefix-length information, and an interface ID that is both random and unique.It should use the information that is contained in the RA message and contact a DHCPv6 server for additional information.It should use the information that is contained in the RA message exclusively.It should contact a DHCPv6 server for all the information that it needs.
Explanation: ICMPv6 RA messages contain two flags to indicate whether a workstation should use SLAAC, a DHCPv6 server, or a combination to configure its IPv6 address. These two flags are M flag and O flag. When both flags are 0 (by default), a client must only use the information in the RA message. When M flag is 0 and O flag is 1, a client should use the information in the RA message and look for the other configuration parameters (such as DNS server addresses) on DHCPv6 servers.

21. Refer to the exhibit. What should be done to allow PC-A to receive an IPv6 address from the DHCPv6 server?

Add the ipv6 dhcp relay command to interface Fa0/0.Change the ipv6 nd managed-config-flag command to ipv6 nd other-config-flag.Configure the ipv6 nd managed-config-flag command on interface Fa0/1.Add the IPv6 address 2001:DB8:1234:5678::10/64 to the interface configuration of the DHCPv6 server.
Explanation: Client DHCPv6 messages are sent to a multicast address with link-local scope, which means that the messages will not be forwarded by routers. Because the client and server are on different subnets on different interfaces, the message will not reach the server. The router can be configured to relay the DHCPv6 messages from the client to the server by configuring the ipv6 dhcp relay command on the interface that is connected to the client.

22. Refer to the exhibit. A network administrator is implementing the stateless DHCPv6 operation for the company. Clients are configuring IPv6 addresses as expected. However, the clients are not getting the DNS server address and the domain name information configured in the DHCP pool. What could be the cause of the problem?

The DNS server address is not on the same network as the clients are on.The router is configured for SLAAC operation.The GigabitEthernet interface is not activated.The clients cannot communicate with the DHCPv6 server, evidenced by the number of active clients being 0.
Explanation: The router is configured for SLAAC operation because there is no configuration command to change the RA M and O flag value. By default, both M and O flags are set to 0. In order to permint stateless DHCPv6 operation, the interface command ipv6 nd other-config-flag should be issued. The GigabitEthernet interface is in working condition because clients can get RA messages and configure their IPv6 addresses as expected. Also, the fact that R1 is the DHCPv6 server and clients are getting RA messages indicates that clients can communicate with the DHCP server. The number of active clients is 0 because the DHCPv6 server does not maintain the state of clients IPv6 addresses (it is not configured for stateful DHCPv6 operation). The DNS server address issue is not relevant to the problem.

23. Question as presented:

A stateless DHCPv6 client would send a DHCPv6 INFORMATION-REQUEST message as step 3 in the process.

24. A company uses the SLAAC method to configure IPv6 addresses for the employee workstations. Which address will a client use as its default gateway?​

the global unicast address of the router interface that is attached to the networkthe unique local address of the router interface that is attached to the networkthe all-routers multicast addressthe link-local address of the router interface that is attached to the network
Explanation: When a PC is configured to use the SLAAC method for configuring IPv6 addresses, it will use the prefix and prefix-length information that is contained in the RA message, combined with a 64-bit interface ID (obtained by using the EUI-64 process or by using a random number that is generated by the client operating system), to form an IPv6 address. It uses the link-local address of the router interface that is attached to the LAN segment as its IPv6 default gateway address.

25. Refer to the exhibit. A network administrator is configuring a router for DHCPv6 operation. Which conclusion can be drawn based on the commands?

The router is configured for stateful DHCPv6 operation, but the DHCP pool configuration is incomplete.The DHCPv6 server name is ACAD_CLASS.Clients would configure the interface IDs above 0010.The router is configured for stateless DHCPv6 operation.
Explanation: The DHCPv6 is for the stateless DHCPv6 operation that is indicated by changing the O flag to 1 and leaving the M flag as default, which is 0. Therefore, it is not configured for stateful DHCPv6 operation. Although the DNS server has the interface ID 0010, clients in stateless DHCPv6 operation will configure their interface IDs either by EUI-64 or a random number. The ACAD_CLASS is the name of the DHCP pool, not the DHCP server name.

26. A network administrator is analyzing the features that are supported by different first-hop router redundancy protocols. Which statement describes a feature that is associated with HSRP?

HSRP uses active and standby routers.HSRP is nonproprietary.It allows load balancing between a group of redundant routers.It uses ICMP messages in order to assign the default gateway to hosts.
Explanation: The HSRP first-hop router redundancy protocol is Cisco proprietary and supports standby and active devices. VRRPv2 and VRRPv3 are nonproprietary. GLBP is Cisco proprietary and supports load balancing between a group of redundant routers.

27. Refer to the exhibit. What protocol can be configured on gateway routers R1 and R2 that will allow traffic from the internal LAN to be load balanced across the two gateways to the Internet?

GLBPPVST+PVSTSTP
Explanation: GLBP, or Group Load Balancing Protocol, allows multiple routers to act as a single default gateway for hosts. GLBP load balances the traffic across the individual routers on a per host basis.

28. Refer to the exhibit. A network engineer is troubleshooting host connectivity on a LAN that uses a first hop redundancy protocol. Which IPv4 gateway address should be configured on the host?

192.168.2.0192.168.2.1192.168.2.2192.168.2.100
Explanation: The host default gateway address should be the FHRP (in this case GLBP) virtual IP address.

29. Refer to the exhibit. Which destination MAC address is used when frames are sent from the workstation to the default gateway?

MAC address of the virtual routerMAC address of the standby routerMAC addresses of both the forwarding and standby routersMAC address of the forwarding router
Explanation: The IP address of the virtual router acts as the default gateway for all the workstations. Therefore, the MAC address that is returned by the Address Resolution Protocol to the workstation will be the MAC address of the virtual router.

30. Question as presented:

Hot Standby Router Protocol (HSRP) is a Cisco-proprietary protocol that is designed to allow for transparent failover of a first-hop IPv4 device.

31. Which FHRP implementation is a Cisco-proprietary protocol that suppports IPv4 load sharing?

IRDPGLBPVRRPv3GLBP for IPv6
32. The address pool of a DHCP server is configured with 10.92.71.0/25. The network administrator reserves 8 IP addresses for servers. How many IP addresses are left in the pool to be assigned to other hosts?

122118119108116
Explanation: Calculate the maximum number of hosts available for the slash value and subtract the required static IP addresses required for the devices.
/24 = 254 hosts
/25 = 126 hosts
/26 = 62 hosts
/27 = 30 hosts
/28 = 14 hosts

33. Question as presented:

The broadcast DHCPDISCOVER message finds DHCPv4 servers on the network. When the DHCPv4 server receives a DHCPDISCOVER message, it reserves an available IPv4 address to lease to the client and sends the unicast DHCPOFFER message to the requesting client. When the client receives the DHCPOFFER from the server, it sends back a DHCPREQUEST. On receiving the DHCPREQUEST message the server replies with a unicast DHCPACK message. DHCPREPLY and DHCPINFORMATION-REQUEST are DHCPv6 messages.

34. After a host has generated an IPv6 address by using the DHCPv6 or SLAAC process, how does the host verify that the address is unique and therefore usable?

The host sends an ICMPv6 echo request message to the DHCPv6 or SLAAC-learned address and if no reply is returned, the address is considered unique.The host sends an ICMPv6 neighbor solicitation message to the DHCP or SLAAC-learned address and if no neighbor advertisement is returned, the address is considered unique.The host checks the local neighbor cache for the learned address and if the address is not cached, it it considered unique.The host sends an ARP broadcast to the local link and if no hosts send a reply, the address is considered unique.
Explanation: Before a host can actually configure and use an IPv6 address learned through SLAAC or DHCP, the host must verify that no other host is already using that address. To verify that the address is indeed unique, the host sends an ICMPv6 neighbor solicitation to the address. If no neighbor advertisement is returned, the host considers the address to be unique and configures it on the interface.

35. Which statement describes HSRP?​

It is used within a group of routers for selecting an active device and a standby device to provide gateway services to a LAN.It uses ICMP to allow IPv4 hosts to locate routers that provide IPv4 connectivity to remote IP networks.​If the virtual router master fails, one router is elected as the virtual router master with the other routers acting as backups.It is an open standard protocol.
Explanation: It is VRRP that elects one router as the virtual router master, with the other routers acting as backups in case the virtual router master fails. HSRP is a Cisco-proprietary protocol. IRDP uses ICMP messages to allow IPv4 hosts to locate routers that provide IPv4 connectivity to other (nonlocal) IP networks. HSRP selects active and standby routers to provide gateway services to hosts on a LAN.

36.Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.

What is the keyword that is displayed on www.netacad.com?

DHCPswitchRouternetworkingCiscoIPv6
Explanation: In order for the host to receive the address of the DNS server, the host must use stateless DHCPv6. The router is configured with the correct DHCPv6 pool, but is missing the command ipv6 nd other-config-flag that signals to the host that it should use DHCPv6 to get additional address information. This command should be added to the interface Gigabit0/0 configuration on the router.

37. Match each DHCP message type with its description. (Not all options are used.)

Explanation: Place the options in the following order:

a client initiating a message to find a DHCP server – DHCPDISCOVERa DHCP server responding to the initial request by a client – DHCPOFFERthe client accepting the IP address provided by the DHCP server – DHCPREQUESTthe DHCP server confirming that the lease has been accepted – DHCPACK
38. Match the purpose with its DHCP message type. (Not all options are used.)

Explanation: The DHCPDISCOVER message is used to identify any DHCP servers on a network. The DHCPOFFER message is used by a server to offer a lease to a client. The DHCPREQUEST message is used to identify both the specific DHCP server and the lease that the client is accepting.
The DHCPACK message is used by a server to finalize a successful lease with a client.
The DHCPNAK message is used when an offered lease is no longer valid.

39. Match the DHCP message types to the order of the stateful DHCPv6 process when a client first connects to an IPv6 network. (Not all options are used.)

40. Match the step number to the sequence of stages that occur during the HSRP failover process. (Not all options are used.)

Explanation: Hot Standby Router Protocol (HSRP) is a Cisco-proprietary protocol that is designed to allow for transparent failover of a first-hop IPv4 device.

41. Match the FHRP protocols to the appropriate description. (Not all options are used.)

42. Match the DHCP message types to the order of the DHCPv4 process. (Not all options are used.)

Explanation: The broadcast DHCPDISCOVER message finds DHCPv4 servers on the network. When the DHCPv4 server receives a DHCPDISCOVER message, it reserves an available IPv4 address to lease to the client and sends the unicast DHCPOFFER message to the requesting client. When the client receives the DHCPOFFER from the server, it sends back a DHCPREQUEST. On receiving the DHCPREQUEST message the server replies with a unicast DHCPACK message. DHCPREPLY and DHCPINFORMATION-REQUEST are DHCPv6 messages.

43. The address pool of a DHCP server is configured with 192.168.234.0/27. The network administrator reserves 22 IP addresses for IP phones. How many IP addresses are left in the pool to be assigned to other hosts?

10082118
Explanation: Calculate the maximum number of hosts available for the slash value and subtract the required static IP addresses required for the devices.
/24 = 254 hosts
/25 = 126 hosts
/26 = 62 hosts
/27 = 30 hosts
/28 = 14 hosts

44. A company uses DHCP servers to dynamically assign IPv4 addresses to employee workstations. The address lease duration is set as 5 days. An employee returns to the office after an absence of one week. When the employee boots the workstation, it sends a message to obtain an IP address. Which Layer 2 and Layer 3 destination addresses will the message contain?

both MAC and IPv4 addresses of the DHCP serverFF-FF-FF-FF-FF-FF and IPv4 address of the DHCP serverFF-FF-FF-FF-FF-FF and 255.255.255.255MAC address of the DHCP server and 255.255.255.255
Explanation:When the lease of a dynamically assigned IPv4 address has expired, a workstation will send a DHCPDISCOVER message to start the process of obtaining a valid IP address. Because the workstation does not know the addresses of DHCP servers, it sends the message via broadcast, with destination addresses of FF-FF-FF-FF-FF-FF and 255.255.255.255.

45. Which command will allow a network administrator to check the IP address that is assigned to a particular MAC address?

Router# show running-config I section_dhcpRouter# show ip dhcp server statisticsRouter# show ip dhcp bindingRouter# show ip dhcp pool
Explanation: The show ip dhcp binding command will show the leases, including IP addresses, MAC addresses, lease expiration, type of lease, client ID, and user name.

46. What is the reason that an ISP commonly assigns a DHCP address to a wireless router in a SOHO environment?

better network performancebetter connectivityeasy IP address managementeasy configuration on ISP firewall
Explanation:In a SOHO environment, a wireless router connects to the ISP via a DSL or cable modem. The IP address between the wireless router and ISP site is typically assigned by the ISP through DHCP. This method facilitates the IP addressing management in that IP addresses for clients are dynamically assigned so that if a client is dropped, the assigned IP address can be easily reassigned to another client.

47. What information can be verified through the show ip dhcp binding command?

the IPv4 addresses that are assigned to hosts by the DHCP serverthat DHCPv4 discover messages are still being received by the DHCP serverthe IPv4 addresses that have been excluded from the DHCPv4 poolthe number of IP addresses remaining in the DHCP pool
Explanation:The show ip dhcp binding command shows a list of IPv4 addresses and the MAC addresses of the hosts to which they are assigned. Using this information an administrator can determine which host interfaces have been assigned to specific hosts.

48. What is the result of a network technician issuing the command ip dhcp excluded-address 10.0.15.1 10.0.15.15 on a Cisco router?

The Cisco router will exclude only the 10.0.15.1 and 10.0.15.15 IP addresses from being leased to DHCP clients.The Cisco router will exclude 15 IP addresses from being leased to DHCP clients.The Cisco router will automatically create a DHCP pool using a /28 mask.The Cisco router will allow only the specified IP addresses to be leased to clients.
Explanation: The ip dhcp excluded-address command is followed by the first and the last addresses to be excluded from being leased to DHCP clients.

49. Match the descriptions to the corresponding DHCPv6 server type. (Not all options are used.)

50. Refer to the exhibit. Based on the output that is shown, what kind of IPv6 addressing is being configured?

CCNA 2 v7 Modules 7 – 9: Available and Reliable Networks Exam Answers

stateless DHCPv6SLAACstatic link-localstateful DHCPv6
Explanation: Stateful DHCPv6 pools are configured with address prefixes for hosts via the address command, whereas stateless DHCPv6 pools typically only contain information such as DNS server addresses and the domain name. RA messages that are sent from routers that are configured as stateful DHCPv6 servers have the M flag set to 1 with the command ipv6 nd managed-config-flag, whereas stateless DHCPv6 servers are indicated by setting the O flag to 1 with the ipv6 nd other-config-flag command.

51. Which FHRP implementation is a Cisco-proprietary protocol that suppports IPv6 load balancing?

GLBPGLBP for IPv6VRRPv3VRRPv2
52. Which set of commands will configure a router as a DHCP server that will assign IPv4 addresses to the 192.168.100.0/23 LAN while reserving the first 10 and the last addresses for static assignment?

ip dhcp excluded-address 192.168.100.1 192.168.100.9
ip dhcp excluded-address 192.168.101.254
ip dhcp pool LAN-POOL-100
ip network 192.168.100.0 255.255.254.0
ip default-gateway 192.168.100.1

dhcp pool LAN-POOL-100
ip dhcp excluded-address 192.168.100.1 192.168.100.9
ip dhcp excluded-address 192.168.100.254
network 192.168.100.0 255.255.254.0
default-router 192.168.101.1

ip dhcp excluded-address 192.168.100.1 192.168.100.10
ip dhcp excluded-address 192.168.100.254
ip dhcp pool LAN-POOL-100
network 192.168.100.0 255.255.255.0
ip default-gateway 192.168.100.1

ip dhcp excluded-address 192.168.100.1 192.168.100.10
ip dhcp excluded-address 192.168.101.254
ip dhcp pool LAN-POOL-100
network 192.168.100.0 255.255.254.0
default-router 192.168.100.1

Explanation: The /23 prefix is equivalent to a network mask of 255.255.254.0. The network usable IPv4 address range is 192.168.100.1 to 192.168.101.254 inclusive. The commands dhcp pool, ip default-gateway, and ip network are not valid DHCP configuration commands.

53. What is a result when the DHCP servers are not operational in a network?

Workstations are assigned with the IP address 127.0.0.1.Workstations are assigned with IP addresses in the 10.0.0.0/8 network.Workstations are assigned with IP addresses in the 169.254.0.0/16 network.Workstations are assigned with the IP address 0.0.0.0.
Explanation: When workstations are configured with obtaining IP address automatically but DHCP servers are not available to respond to the requests, a workstation can assign itself an IP addresses from the 169.254.0.0/16 network.

54. A company uses the method SLAAC to configure IPv6 addresses for the workstations of the employees. A network administrator configured the IPv6 address on the LAN interface of the router. The interface status is UP. However, the workstations on the LAN segment did not obtain the correct prefix and prefix length. What else should be configured on the router that is attached to the LAN segment for the workstations to obtain the information?​

R1(config)# ipv6 dhcp pool
R1(config-if)# ipv6 enable
R1(config)# ipv6 unicast-routing
R1(config-if)# ipv6 nd other-config-flag

Explanation: A PC that is configured to use the SLAAC method obtains the IPv6 prefix and prefix length from a router. When the PC boots, it sends an RS message to inform the routers that it needs the information. A router sends an RA message that includes the required information. For a router to be able to send RA messages, it must be enabled as an IPv6 router by the unicast ipv6-routing command in global configuration mode. The other options are not used to enable IPv6 routing on a router.

55. Which FHRP implementation is a nonproprietary protocol which relies on ICMP to provide IPv4 redundancy?

VRRPv3GLBP for IPv6IRDPGLBP
56. Refer to the exhibit. PC-A is unable to receive an IPv6 address from the stateful DHCPv6 server. What is the problem?

The ipv6 dhcp relay command should be applied to interface Gig0/0.The ipv6 nd managed-config-flag should be applied to interface Gig0/1.The ipv6 dhcp relay command should use the link-local address of the DHCP server.The ipv6 nd managed-config-flag command should be ipv6 nd other-config-flag .
Explanation: The ipv6 dhcp relay command must be applied to the interface where the clients are located. The ipv6 dhcp relay command can use either the link-local or global unicast address of the DHCPv6 server, or even a multicast address. The ipv6 nd managed-config-flag indicates to the clients that they should use stateful DHCPv6 and is also applied to the interface where the clients are located.

57. Refer to the exhibit. A network administrator is configuring a router as a DHCPv6 server. The administrator issues a show ipv6 dhcp pool command to verify the configuration. Which statement explains the reason that the number of active clients is 0?

The default gateway address is not provided in the pool.No clients have communicated with the DHCPv6 server yet.The IPv6 DHCP pool configuration has no IPv6 address range specified.The state is not maintained by the DHCPv6 server under stateless DHCPv6 operation.
Explain:
Under the stateless DHCPv6 configuration, indicated by the command ipv6 nd other-config-flag, the DHCPv6 server does not maintain the state information, because client IPv6 addresses are not managed by the DHCP server. Because the clients will configure their IPv6 addresses by combining the prefix/prefix-length and a self-generated interface ID, the ipv6 dhcp pool configuration does not need to specify the valid IPv6 address range. And because clients will use the link-local address of the router interface as the default gateway address, the default gateway address is not necessary.

58. Which FHRP implementation is Cisco-proprietary and permits only one router in a group to forward IPv6 packets?

VRRPv3HSRPHSRP for IPv6VRRPv2
59. Which FHRP implementation is a nonproprietary IPv4-only election protocol which has one master router per group?

HSRP for IPv6GLBPVRRPv2VRRPv3
60. The address pool of a DHCP server is configured with 172.18.93.0/25. The network administrator reserves 10 IP addresses for web servers. How many IP addresses are left in the pool to be assigned to other hosts?

106117114120116
Explain:
Calculate the maximum number of hosts available for the slash value and subtract the required static IP addresses required for the devices.
/24 = 254 hosts
/25 = 126 hosts
/26 = 62 hosts
/27 = 30 hosts
/28 = 14 hosts

61. The address pool of a DHCP server is configured with 10.3.2.0/24. The network administrator reserves 3 IP addresses for printers. How many IP addresses are left in the pool to be assigned to other hosts?

252241255249251
Explain: CIDR Subnet Calculator Online

62. The address pool of a DHCP server is configured with 172.23.143.0/26. The network administrator reserves 14 IP addresses for file servers. How many IP addresses are left in the pool to be assigned to other hosts?

5848506140
63. The address pool of a DHCP server is configured with 10.7.30.0/24. The network administrator reserves 5 IP addresses for printers. How many IP addresses are left in the pool to be assigned to other hosts?

253239249250247
Explain: Calculate the maximum number of hosts available for the slash value and subtract the required static IP addresses required for the devices.
/24 = 254 hosts
/25 = 126 hosts
/26 = 62 hosts
/27 = 30 hosts
/28 = 14 hosts

64. Which FHRP implementation is a nonproprietary IPv4-only election protocol with limited scalability?

VRRPv2GLBPGLBP for IPv6IRDP
65. The address pool of a DHCP server is configured with 192.168.184.0/26. The network administrator reserves 18 IP addresses for access points. How many IP addresses are left in the pool to be assigned to other hosts?

5744543646
66. The address pool of a DHCP server is configured with 10.19.44.0/24. The network administrator reserves 3 IP addresses for servers. How many IP addresses are left in the pool to be assigned to other hosts?

255252241251249
67. The address pool of a DHCP server is configured with 10.19.44.0/24. The network administrator reserves 6 IP addresses for servers. How many IP addresses are left in the pool to be assigned to other hosts?

246252249248238
68. The address pool of a DHCP server is configured with 172.21.121.0/25. The network administrator reserves 12 IP addresses for web servers. How many IP addresses are left in the pool to be assigned to other hosts?

115114118104112
Explanation: Calculate the maximum number of hosts available for the slash value and subtract the required static IP addresses required for the devices.
/24 = 254 hosts
/25 = 126 hosts
/26 = 62 hosts
/27 = 30 hosts
/28 = 14 hosts

69. Which kind of message is sent by a DHCP client when its IP address lease is about to expire?​

a DHCPREQUEST broadcast message​a DHCPDISCOVER unicast message​a DHCPDISCOVER broadcast messagea DHCPREQUEST unicast message​
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