CISCO CCNA - Book 1, Chapter 5

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CISCO CCNA - Book 1, Chapter 5

OSI Network Layer The method described by the network layer for routing packets from a device on one network to a device on a different network How the Internet Protocol (IP) works at the network layer to provide connectionless, best-effort service to the upper layers of the OSI model How devices are grouped into physical and logical networks How the heirarchical addresses of devices allow communication between networks How routers use next-hop addresses to select a path for packets to reach their destination How routers forward packets


Questions and Answers
  • 1. 
    Refer to the exhibit. A network administrator notices that there are too many broadcasts on the network. What two steps can the network administrator take to resolve this problem? (Choose two)
    • A. 

      Replace S2 with a router

    • B. 

      Place all servers on S1

    • C. 

      Disable TCP/IP broadcasts

    • D. 

      Subnet the 192.168.0.0 /24 network

    • E. 

      Disable all unused interfaces on the switches

  • 2. 
    Refer to the exhibit. The network in the exhibit is fully operational. What two statements correctly describe the routing for the topology that is shown? (Choose two)
    • A. 

      192.168.0.2 is the next-hop address that is used by R3 to route a packet from the 10.0.0.0 network to the 172.16.0.0 network

    • B. 

      10.0.0.1 is the next-hop address that is used by R1 to route a packet from the 192.168.12.0 network to the 10.0.0.0 network

    • C. 

      192.168.0.1 is the next-hop address that is used by R1 to route a packet from the 192.168.12.0 network to the 172.16.0.0 network

    • D. 

      172.16.0.1 is the next-hop address that is used by R3 to route a packet from the 10.0.0.0 to the 172.16.0.0 network

    • E. 

      192.168.0.1 is the next-hop address that is used by R2 to route a packet from the 172.16.0.0 network to the 192.168.12.0 network

    • F. 

      192.168.0.2 is the next-hop address that is used by R2 to route a packet from the 172.16.0.0 network to the 192.168.12.0 network

  • 3. 
    Refer to the exhibit. Using the network in the exhibit, what would be the default gateway address for host A in the 192.133.219.0 network?
    • A. 

      192.135.250.1

    • B. 

      192.31.7.1

    • C. 

      192.133.219.0

    • D. 

      192.133.219.1

  • 4. 
    • A. 

      3

    • B. 

      4

    • C. 

      5

    • D. 

      7

    • E. 

      8

    • F. 

      11

  • 5. 
    Refer to the exhibit. A network administrator is troubleshooting a connectivity problem and needs to determine the address that is used to forward network packets out the network. Using the netstat -r command, the administrator would identify which address as the address to which all hosts send packets that are destined for an outside network?
    • A. 

      10.10.10.26

    • B. 

      127.0.0.1

    • C. 

      10.10.10.6

    • D. 

      10.10.10.1

    • E. 

      224.0.0.0

  • 6. 
    In an IPv4 environment, what information is used by the router to forward data packets from one interface of a router to another?
    • A. 

      Destination network address

    • B. 

      Source network address

    • C. 

      Source MAC address

    • D. 

      Well known port destination address

  • 7. 
    What information is added during encapsulation at OSI Layer 3?
    • A. 

      Source and destination MAC

    • B. 

      Source and destination application protocol

    • C. 

      Source and destination port number

    • D. 

      Source and destination IP address

  • 8. 
    In a connectionless system, which of the following is correct?
    • A. 

      The destination is contacted before a packet is sent

    • B. 

      The destination is not contacted before a packet is sent

    • C. 

      The destination sends an acknowledgement to the source that indicates the packet was received

    • D. 

      The destination sends an acknowledgement to the source that requests the next packet to be sent

  • 9. 
    Which IP packet field will prevent endless loops?
    • A. 

      Type-of-service

    • B. 

      Identification

    • C. 

      Flags

    • D. 

      Time-to-live

    • E. 

      Header checksum

  • 10. 
    Which portion of the network layer address does a router use to forward packets?
    • A. 

      Host portion

    • B. 

      Broadcast address

    • C. 

      Network portion

    • D. 

      Gateway address

  • 11. 
    If the default gateway is configured incorrectly on the host, what is the impact on communications?
    • A. 

      The host is unable to communicate on the local network

    • B. 

      The host can communicate with other hosts on the local network, but is unable to communicate with hosts on remote networks

    • C. 

      The host can communicate with other hosts on remote networks, but is unable to communicate with hosts on the local network

    • D. 

      There is no impact on communications

  • 12. 
    What is the purpose of a default gateway?
    • A. 

      Physically connects a computer to a network

    • B. 

      Provides a permanent address to a computer

    • C. 

      Identifies the network to which a computer is connected

    • D. 

      identifies the logical address of a networked computer and uniquely identifies it to the rest of the network

    • E. 

      identifies the device that allows local network computers to communicate with devices on other networks

  • 13. 
    What type of routing uses information that is manually entered into the routing table?
    • A. 

      Dynamic

    • B. 

      Interior

    • C. 

      Static

    • D. 

      Standard

  • 14. 
    When the destination network is not listed in the routing table of a Cisco router, what are two possible actions that the router might take? (Choose two)
    • A. 

      The router sends an ARP request to determine the required next hop address

    • B. 

      The router discards the packet

    • C. 

      The router forwards the packet toward the next hop indicated in the ARP table

    • D. 

      The router forwards the packet to the interface indicated by the source address

    • E. 

      The router forwards the packet out the interface indicated by the default route entry

  • 15. 
    What are the key factors to consider when grouping hosts into a common network? (Choose three)
    • A. 

      Gateways

    • B. 

      Purpose

    • C. 

      Physical addressing

    • D. 

      Software version

    • E. 

      Geographic location

    • F. 

      Ownership

  • 16. 
    What is a component of a routing table entry?
    • A. 

      The MAC address of the interface of the router

    • B. 

      The destination Layer 4 port number

    • C. 

      The destination host address

    • D. 

      The next-hop address

  • 17. 
    Which intermediary devices could be used to implement security between networks? (Choose two)
    • A. 

      Router

    • B. 

      Hub

    • C. 

      Switch

    • D. 

      Firewall

    • E. 

      Access point

    • F. 

      Bridge

  • 18. 
    What are three common problems with a large network? (Choose three)
    • A. 

      Too few broadcasts

    • B. 

      Performance degradation

    • C. 

      Security issues

    • D. 

      Limited management responsibility

    • E. 

      Host identification

    • F. 

      Protocol compatibility

  • 19. 
    Which three statements are true about routes and their use? (Choose three)
    • A. 

      If no route to the destination network is found, the packet is returned to the previous router

    • B. 

      If the destination network is directly connected, the router forwards the packet to the destination host

    • C. 

      If multiple network entries exist for the destination network, the most general route is used to forward the packet

    • D. 

      If no route exists for the destination network and a default route is present, the packet is forwarded to the next-hop router

    • E. 

      If the originating host has a default gateway configured, the packet for a remote network can be forwarded using that route

    • F. 

      If a host does not have a route manually configured for the destination network, the host will drop the packet

  • 20. 
    What two characteristics are commonly associated with dynamic routing protocols? (Choose two)
    • A. 

      Require no device configuration

    • B. 

      Provide routers with up-to-date routing tables

    • C. 

      Require less processing power than static routes require

    • D. 

      Consume bandwidth to exchange route information

    • E. 

      Prevent manual configuration and maintenance of the routing table

  • 21. 
    What statement describes the purpose of a default route?
    • A. 

      A host uses a default route to transfer data to another host on the same network segment

    • B. 

      A host uses a default route to forward data to the local switch as the next hop to all destinations

    • C. 

      A host uses a default route to identify the Layer 2 address of an end device on the local network

    • D. 

      A host uses a default route to transfer data to a host outside the local network when no other route to the destination exists

  • 22. 
    Which protocol provides connectionless network layer services?
    • A. 

      IP

    • B. 

      TCP

    • C. 

      UDB

    • D. 

      OSI

  • 23. 
    What two commands can be used to view a host's routing table? Please separate answers with a comma and a space.
  • 24. 
    Select three pieces of information about a route that a routing table contains.
    • A. 

      Next-hop

    • B. 

      Source address

    • C. 

      Metric

    • D. 

      Destination network address

    • E. 

      Last hop

    • F. 

      Default gateway

  • 25. 
    What kinds of problems are caused by excessive broadcast traffic on a network segment? (Choose three)
    • A. 

      Consumes network bandwidth

    • B. 

      Increases overhead on network

    • C. 

      Requires complex address schemes

    • D. 

      Interrupts other host functions

    • E. 

      Divides networks based on ownership

    • F. 

      Advanced hardware required

  • 26. 
    Which of the following are not functions of the network layer? (Choose two)
    • A. 

      Routing

    • B. 

      Addressing packets with an IP address

    • C. 

      Delivery reliability

    • D. 

      Application data analysis

    • E. 

      Encapsulation

    • F. 

      Decapsulation

  • 27. 
    Which of the following are true about IP? (Choose two)
    • A. 

      IP stands for International Protocol

    • B. 

      It is the most common network layer protocol

    • C. 

      It analyses presentation layer data

    • D. 

      It operates at OSI layer 2

    • E. 

      It encapsulates transport layer segments

  • 28. 
    What is the name of the process of removing the OSI layer 2 information from an IP packet?
  • 29. 
    Which of the following is true about IP?
    • A. 

      It is connection-oriented

    • B. 

      It uses application data to determine the best path

    • C. 

      It is used by both routers and hosts

    • D. 

      It is reliable

  • 30. 
    Which of the following are true about network layer encapsulation? (Choose two)
    • A. 

      It adds a header to a segment

    • B. 

      It can happen many times on the path to the destination host

    • C. 

      It is performed by the last router on the path

    • D. 

      Both source and destination IP addresses are added

    • E. 

      It converts transport layer information into a frame

  • 31. 
    • A. 

      TCP is connectionless and IP is connection oriented

    • B. 

      TCP is reliable and IP is unreliable

    • C. 

      IP is connectionless and TCP is connection oriented

    • D. 

      TCP is unreliable and IP is reliable

    • E. 

      IP operates at the transport layer

  • 32. 
    Why is IP "media independent"?
    • A. 

      It encapsulates layer 1 instructions

    • B. 

      It works the same on all layer 1 media

    • C. 

      It carries both video and voice data

    • D. 

      It works without layer 1 media

  • 33. 
    TCP is a __________ layer protocol.
  • 34. 
    How many bits are in an IPv4 address?
  • 35. 
    Which of the following are true about static and dynamic routing? (Choose two)
    • A. 

      Static routing requires a routing protocol such as RIP

    • B. 

      A default route is a dynamic route

    • C. 

      Dynamic routing adds packet-processing overhead

    • D. 

      Administrative overhead is reduced with static routing

    • E. 

      Routers can use static and dynamic routing simultaneously

  • 36. 
    What can happen when the TTL is 1? (Choose two)
    • A. 

      The packet can be successfully delivered if it is destined for a directly connected network

    • B. 

      TCP controls in the packet will add hops to the TTL

    • C. 

      The packet will be dropped by the next router unless that router has an interface on the destination network

    • D. 

      The packet will be returned to the source host

    • E. 

      The packet will be returned to the previous router

  • 37. 
    IP is connectionless and will occasionally drop a packet en route to a destination IP address. If packets are dropped, how will messages be completed?
    • A. 

      Only the IP portion of the packet is dropped, but the TCP portion continues to the last router

    • B. 

      The routing protocols will carry the TCP information to the previous-hop router, which sends a reverse notification to the source

    • C. 

      The routing protocols, such as RIP, are connection oriented and will contact the source host

    • D. 

      The destination host is expecting the packet and will send a request if it does not arrive

    • E. 

      The IP header contains the source address so that the packet can be returned by the router that receives the packet when TTL is 0