CCNA2 v6.0 Chapter 9 Exam Answers 2019

Last Updated on October 25, 2019 by Admin

CCNA2 v6.0 Chapter 9 Exam Answers 2019

1. What is the primary purpose of NAT?

   • conserve IPv4 addresses
   • increase network security
   • allow peer-to-peer file sharing
   • enhance network performance
     

     Explanation: NAT was developed to conserve IPv4 addresses. A side benefit is that NAT adds a small level of security by hiding the internal network addressing scheme. However, there are some drawbacks of using NAT. It does not allow true peer-to-peer communication and it adds latency to outbound connections.

2. Which method is used by a PAT-enabled router to send incoming packets to the correct inside hosts?​

   • It uses the destination TCP or UDP port number on the incoming packet.
   • It uses the source TCP or UDP port number on the incoming packet.
   • It uses the source IP address on the incoming packet.
   • It uses a combination of the source TCP or UDP port number and the destination IP address on the incoming packet.
     

     Explanation: A PAT-enabled router maintains a table that consists of a mapping of inside local IP addresses and TCP/UDP port numbers to outside local addresses and TCP/UDP port numbers. When traffic returns to the router from the public network, the router would compare the destination port to the PAT mapping table to determine to which inside host the traffic should be sent.

3. A technician is required to configure an edge router to use a different TCP port number for each session with a server on the Internet. What type of Network Address Translation (NAT) should be implemented?

   • a one-to-one address mapping between local and global addresses
   • a many-to-many address mapping between local and global addresses
   • a many-to-one address mapping between local and global addresses
   • a one-to-many address mapping between local and global addresses
     

     Explanation: Port Address Translation is also known as NAT overloading. PAT uses ports as an additional parameter to provide a multiplier effect, making it possible to reuse any one of the 10 inside global addresses up to 65,536 times.

4. What are two benefits of NAT? (Choose two.)

   • It saves public IP addresses.
   • It adds a degree of privacy and security to a network.
   • It increases routing performance.
   • It makes troubleshooting routing issues easier.
   • It makes tunneling with IPsec less complicated.

5. What is a disadvantage of NAT?

   • There is no end-to-end addressing.
   • The router does not need to alter the checksum of the IPv4 packets.​
   • The internal hosts have to use a single public IPv4 address for external communication.
   • The costs of readdressing hosts can be significant for a publicly addressed network.​
     

     Explanation: Many Internet protocols and applications depend on end-to-end addressing from the source to the destination. Because parts of the header of the IP packets are modified, the router needs to alter the checksum of the IPv4 packets. Using a single public IP address allows for the conservation of legally registered IP addressing schemes. If an addressing scheme needs to be modified, it is cheaper to use private IP addresses.

6. What is an advantage of deploying IPv4 NAT technology for internal hosts in an organization?

   • makes internal network access easy for outside hosts using UDP
   • provides flexibility in designing the IPv4 addressing scheme
   • increases the performance of packet transmission to the Internet
   • enables the easy deployment of applications that require end-to-end traceability
     

     Explanation: IPv4 NAT provides some benefits: – NAT conserves the legally registered addressing scheme. – NAT increases the flexibility of connections to the public network. – NAT provides consistency for internal network addressing schemes. – NAT provides certain level of network security by hiding the internal network topology and hosts. IPv4 NAT also brings some disadvantages: – NAT may impact the network performance due to the translation process – End-to-end addressing is lost, especially when dynamic NAT is used. – End-to-end IPv4 traceability is also lost. – NAT complicates tunneling protocols, such as IPsec. – Services that require the initiation of TCP connections from the outside network, or stateless protocols, such as those using UDP, can be disrupted.

7. Refer to the exhibit. Which address or addresses represent the inside global address?

   

   CCNA 2 RSE 6.0 Chapter 9 Exam Answers 2018 2019 02

   • 10.1.1.2
   • 192.168.0.100
   • 209.165.20.25
   • any address in the 10.1.1.0 network

8. Refer to the exhibit. A technician is configuring R2 for static NAT to allow the client to access the web server. What is a possible reason that the client PC cannot access the web server?

   

   CCNA 2 RSE 6.0 Chapter 9 Exam Answers 2018 2019 04

   • Interface S0/0/0 should be identified as the outside NAT interface.
   • Interface Fa0/1 should be identified as the outside NAT interface.
   • The IP NAT statement is incorrect.
   • The configuration is missing a valid access control list.
     

     Explanation: Interface S0/0/0 should be identified as the outside NAT interface. The command to do this would be R2(config-if)# ip nat outside.

9. A network administrator configures the border router with the command R1(config)# ip nat inside source list 4 pool corp. What is required to be configured in order for this particular command to be functional?

   • a NAT pool named corp that defines the starting and ending public IP addresses
   • an access list named corp that defines the private addresses that are affected by NAT
   • an access list numbered 4 that defines the starting and ending public IP addresses
   • ip nat outside to be enabled on the interface that connects to the LAN affected by the NAT
   • a VLAN named corp to be enabled and active and routed by R1
     

     Explanation: In order for the ip nat inside source list 4 pool corp command to work, the following procedure needs to be used beforehand:Create an access list that defines the private IP addresses affected by NAT. Establish a NAT pool of starting and ending public IP addresses by using the ip nat pool command. Use the ip nat inside source list command to associate the access list with the NAT pool. Apply NAT to internal and external interfaces by using the ip nat inside and ip nat outside commands.

10. When dynamic NAT without overloading is being used, what happens if seven users attempt to access a public server on the Internet when only six addresses are available in the NAT pool?

    • No users can access the server.
    • The request to the server for the seventh user fails.
    • All users can access the server.
    • The first user gets disconnected when the seventh user makes the request.
      

      Explanation: If all the addresses in the NAT pool have been used, a device must wait for an available address before it can access the outside network.

11. What is defined by the ip nat pool command when configuring dynamic NAT?

    • the pool of global address
    • the range of internal IP addresses that are translated
    • the pool of available NAT servers
    • the range of external IP addresses that internal hosts are permitted to access
      

      Explanation: Dynamic NAT uses a pool of inside global addresses that are assigned to outgoing sessions. Creating the pool of inside global addresses is accomplished using the ip nat pool command.

12. Refer to the exhibit. What is the purpose of the command marked with an arrow shown in the partial configuration output of a Cisco broadband router?

    

    CCNA 2 RSE 6.0 Chapter 9 Exam Answers 2018 2019 01

    • defines which addresses can be translated
    • defines which addresses are allowed into the router
    • defines which addresses are assigned to a NAT pool
    • defines which addresses are allowed out of the router

13. A network engineer has configured a router with the command ip nat inside source list 4 pool corp overload. Why did the engineer use the overload option?

    • The company has more private IP addresses than available public IP addresses.
    • The company needs to have more public IP addresses available to be used on the Internet.
    • The company router must throttle or buffer traffic because the processing power of the router is not enough to handle the normal load of external-bound Internet traffic.
    • The company has a small number of servers that should be accessible by clients from the Internet.
      

      Explanation: The overload option enables PAT for a pool of public IP addresses. The source list 4 part of the command refers to the access list that defines what private addresses get translated. The pool corp part of the command refers to the named NAT pool that is created using the separate ip nat pool corp command.

14. What are two of the required steps to configure PAT? (Choose two.)

    • Define a pool of global addresses to be used for overload translation.
    • Create a standard access list to define applications that should be translated.
    • Define the range of source ports to be used.
    • Identify the inside interface.
    • Define the hello and interval timers to match the adjacent neighbor router.
      

      Explanation: The steps that are required to configure PAT are to define a pool of global addresses to be used for overload translation, to configure source translation by using the keywords interface and overload, and to identify the interfaces that are involved in the PAT.

15. What is the major benefit of using NAT with Port Address Translation?

    • It allows external hosts access to internal servers.
    • It improves network performance for real-time protocols.
    • It allows many internal hosts to share the same public IPv4 address.
    • It provides a pool of public addresses that can be assigned to internal hosts.
      

      Explanation: Port Address Translation (PAT) tracks IP flows of internal hosts using port numbers. By using port numbers to track flows, PAT allows many users to share a single public IPv4 address.

16. What is the purpose of port forwarding?

    • Port forwarding allows an external user to reach a service on a private IPv4 address that is located inside a LAN.
    • Port forwarding allows users to reach servers on the Internet that are not using standard port numbers.
    • Port forwarding allows an internal user to reach a service on a public IPv4 address that is located outside a LAN.
    • Port forwarding allows for translating inside local IP addresses to outside local addresses.
      

      Explanation: Port forwarding allows a user or program from outside to reach services inside a private network. It is not a technique that allows for using services with nonstandard port numbers. NAT or PAT convert inside IP addresses to outside local addresses.

17. A network administrator is configuring a static NAT on the border router for a web server located in the DMZ network. The web server is configured to listen on TCP port 8080. The web server is paired with the internal IP address of 192.168.5.25 and the external IP address of 209.165.200.230. For easy access by hosts on the Internet, external users do not need to specify the port when visiting the web server. Which command will configure the static NAT?

    • R1(config)# ip nat inside source static tcp 192.168.5.25 80 209.165.200.230 8080
    • R1(config)# ip nat inside source static tcp 192.168.5.25 8080 209.165.200.230 80
    • R1(config)# ip nat inside source static tcp 209.165.200.230 80 192.168.5.25 8080
    • R1(config)# ip nat inside source static tcp 209.165.200.230 8080 192.168.5.25 80
      

      Explanation: The IOS command for port forwarding configuration in global configuration mode is as follows: ip nat inside source {static {tcp | udp local-ip local-port global-ip global-port} Where local-ip is the inside local address, local-port is the port on which the web server listens.

18. What is a characteristic of unique local addresses?

    • They allow sites to be combined without creating any address conflicts.
    • They are designed to improve the security of IPv6 networks.
    • Their implementation depends on ISPs providing the service.
    • They are defined in RFC 3927.
      

      Explanation: Link-local addresses are defined in RFC 3927. Unique local addresses are independent of any ISP, and are not meant to improve the security of IPv6 networks.

19. Which statement describes IPv6 ULAs?

    • They conserve IPv6 address space.
    • They are assigned by an ISP.
    • They begin with the fe80::/10 prefix.
    • They are not routable across the Internet.
      

      Explanation: IPv6 ULAs are unique local addresses. ULAs are similar to IPv4 private IP addresses and are not routable on the Internet. ULAs do not conserve IPv6 addresses. ULAs have a network prefix in the fc00::/7 range.

20. Refer to the exhibit. Based on the output that is shown, what type of NAT has been implemented?

    

    CCNA 2 RSE 6.0 Chapter 9 Exam Answers 2018 2019 03

    • dynamic NAT with a pool of two public IP addresses
    • PAT using an external interface
    • static NAT with one entry
    • static NAT with a NAT pool
      

      Explanation: The output shows that there are two inside global addresses that are the same but that have different port numbers. The only time port numbers are displayed is when PAT is being used. The same output would be indicative of PAT that uses an address pool. PAT with an address pool is appropriate when more than 4,000 simultaneous translations are needed by the company.

21. Match the steps with the actions that are involved when an internal host with IP address 192.168.10.10 attempts to send a packet to an external server at the IP address  209.165.200.254 across a router R1 that is running dynamic NAT. (Not all options are used.)

    • Question
      

      CCNA2 v6.0 Chapter 9 Exam Q001

    • Answer
      

      CCNA2 v6.0 Chapter 9 Exam A001

      Explanation: The translation of the IP addresses from 209.65.200.254 to 192.168.10.10 will take place when the reply comes back from the server.

22. Fill in the blank. Do not use abbreviations.

    NAT overload is also known as  Port Address Translation