100-105 practice test

1. Question 1 · 1

   An administrator is working with the 192.168.4.0 netwrok, which has been subnetted with a /26 mask. Which two addresses can be assigned to hosts within the same subnet? (Choose two.)

   Choose all answers that apply.

   • 192.168.4.67
   • 192.168.4.61
   • 192.168.4.128
   • 192.168.4.132
   • 192.168.4.125
   • 192.168.4.63

   Read explanation

   Only the values of host with 67 and 125 fall within the range of /26 CIDR subnet mask, all others lie beyond it.

2. Question 2 · 1

   Refer to the exhibit. The junior network support staff provided the diagram as a recommended configuration for the first phase of a four-phase network expansion project. The entire network expansion will have over 1000 users on 14 network segments and has been allocated this IP address space. ✑ 192.168.1.1 through 192.168.5.255 ✑ 192.168.100.1 through 192.168.100.255 What are three problems with this design? (Choose three.)

   Choose all answers that apply.

   

   • The AREA 1 IP address space is inadequate for the number of users.
   • The AREA 3 IP address space is inadequate for the number of users.
   • AREA 2 could use a mask of /25 to conserve IP address space.
   • The network address space that is provided requires a single network-wide mask.
   • The router-to-router connection is wasting address space.
   • The broadcast domain in AREA 1 is too large for IP to function.

   Read explanation

   The given IP addresses of areas 1 and 3 along with network masks of 24 cannot accommodate 500 users so are inadequate, while the area 2 is having over capacity so its network mask can be reduced to 25 to accommodate the only 60 users it has.

3. Question 3 · 1

   Refer to the exhibit. When running OSPF, what would cause router A not to form an adjacency with router B?

   Choose one answer.

   

   • The loopback addresses are on different subnets.
   • The values of the dead timers on the routers are different.
   • Route summarization is enabled on both routers.
   • The process identifier on router A is different than the process identifier on router B.

   Read explanation

   To form an adjacency (become neighbor), router A & B must have the same Hello interval, Dead interval and AREA numbers

4. Question 4 · 1

   The OSPF Hello protocol performs which of the following tasks? (Choose two.)

   Choose all answers that apply.

   • It provides dynamic neighbor discovery.
   • It detects unreachable neighbors in 90 second intervals.
   • It maintains neighbor relationships.
   • It negotiates correctness parameters between neighboring interfaces.
   • It uses timers to elect the router with the fastest links as the designated router.
   • It broadcasts hello packets throughout the internetwork to discover all routers that are running OSPF.

5. Question 5 · 1

   A workstation has just resolved a browser URL to the IP address of a server. Which protocol will the workstation now use to determine the destination MAC address to be placed into frames directed toward the sever?

   Choose one answer.

   • ARP
   • RARP
   • DNS
   • DHCP
   • HTTP

6. Question 6 · 1

   Refer to the exhibit. A network technician is unable to ping from R1 to R2. What will help correct the problem?

   Choose one answer.

   

   • Ensure that the serial cable is correctly plugged in to the interfaces.
   • Apply the clock rate 56000 configuration command to the serial0/1 interface of R1.
   • Configure the serial0/1 interfaces on R1 and R2 with the no shutdown command.
   • Change the address of the serial0/1 interface of R1 to 192.1.1.4.
   • Change the subnet masks of both interfaces to 255.255.255.240.

7. Question 7 · 1

   Refer to the exhibit. Which two of the output fields could help you determine if a broadcast storm has occurred? (Choose two.)

   Choose all answers that apply.

   

   • giants
   • no buffer
   • collisions
   • ignored
   • dribble condition

8. Question 8 · 1

   Which command can you enter to verify that a 128-bit address is live and responding?

   Choose one answer.

   • traceroute
   • telnet
   • ping
   • ping ipv6

9. Question 9 · 1

   Which device allows users to connect to the network using a single or double radio?

   Choose one answer.

   • access point
   • switch
   • wireless controller
   • firewall

10. Question 10 · 1

    If three devices are plugged into one port on a switch and two devices are plugged into a different port, how many collision domains are on the switch?

    Choose one answer.

    • 2
    • 4
    • 5
    • 6

11. Question 11 · 1

    Refer to the exhibit. Which command is simplest to configure routing between the regional office network 10.89.0.0/20 and the corporate network?

    Choose one answer.

    

    • router2(config)#ip route 0.0.0.0 0.0.0.0 10.89.16.1
    • router2(config)#ip route 10.89.3.0 255.255.0.0 10.89.16.2
    • router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.1
    • router1(config)#ip route 10.89.0.0 255.255.240.0 10.89.16.2

    Read explanation

    The fourth command makes it possible for all hosts beyond R2 and all hosts beyond R1 to interact with each other, hence it is the simplest technique.

12. Question 12 · 1

    Click on the correct location or locations in the exhibit. Which of these destination addresses does not require the use of the default gateway for a packet from this local host?

    Choose one answer.

    

    

    • 10.4.8.2
    • 10.5.2.27
    • 10.68.2.88
    • 172.16.3.228
    • 172.16.236.4

13. Question 13 · 1

    Under which circumstance should a network administrator implement one-way NAT?

    Choose one answer.

    • when the network must route UDP traffic
    • when traffic that originates outside the network must be routed to internal hosts
    • when traffic that originates inside the network must be routed to internal hosts
    • when the network has few public IP addresses and many private IP addresses require outside access

    Read explanation

    NAT operation is typically transparent to both the internal and external hosts. Typically the internal host is aware of the true IP address and TCP or UDP port of the external host. Typically the NAT device may function as the default gateway for the internal host. However the external host is only aware of the public IP address for the NAT device and the particular port being used to communicate on behalf of a specific internal host. NAT and TCP/UDP - "Pure NAT", operating on IP alone, may or may not correctly parse protocols that are totally concerned with IP information, such as ICMP, depending on whether the payload is interpreted by a host on the "inside" or "outside" of translation. As soon as the protocol stack is traversed, even with such basic protocols as TCP and UDP, the protocols will break unless NAT takes action beyond the network layer. IP packets have a checksum in each packet header, which provides error detection only for the header. IP datagrams may become fragmented and it is necessary for a NAT to reassemble these fragments to allow correct recalculation of higher-level checksums and correct tracking of which packets belong to which connection. The major transport layer protocols, TCP and UDP, have a checksum that covers all the data they carry, as well as the TCP/UDP header, plus a "pseudo-header" that contains the source and destination IP addresses of the packet carrying the TCP/UDP header. For an originating NAT to pass TCP or UDP successfully, it must recompute the TCP/UDP header checksum based on the translated IP addresses, not the original ones, and put that checksum into the TCP/UDP header of the first packet of the fragmented set of packets. The receiving NAT must recompute the IP checksum on every packet it passes to the destination host, and also recognize and recompute the TCP/UDP header using the retranslated addresses and pseudo-header. This is not a completely solved problem. One solution is for the receiving NAT to reassemble the entire segment and then recompute a checksum calculated across all packets. The originating host may perform Maximum transmission unit (MTU) path discovery to determine the packet size that can be transmitted without fragmentation, and then set the don't fragment (DF) bit in the appropriate packet header field. Of course, this is only a one- way solution, because the responding host can send packets of any size, which may be fragmented before reaching the NAT.

14. Question 14 · 1

    How can an administrator determine if a router has been configured when it is first powered up?

    Choose one answer.

    • A configured router prompts for a password.
    • A configured router goes to the privileged mode prompt.
    • An unconfigured router goes into the setup dialog.
    • An unconfigured router goes to the enable mode prompt.

15. Question 15 · 1

    Which statement about upgrading a cisco ios device with TFTP is True?

    Choose one answer.

    • The Cisco IOS device must be on the same lan as the TFTP server
    • The operation is performed in passive mode
    • The operation is performed in an unencrypted format
    • The operation is performed in active mode

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