Cisco 100-101 Online Practice Questions and Exam Preparation

Cisco 100-101 Online Questions & Answers

• Question 151:

  

  

  

  Which of the following is true regarding the configuration of SwitchA?

  A. only 5 simultaneous remote connections are possible
  B. remote connections using ssh will require a username and password
  C. only connections from the local network will be possible
  D. console access to SwitchA requires a password
  B. remote connections using ssh will require a username and password

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  Ssh login requires a user name and password always while other conditions may or may not be true.

• Question 152:

  Refer to the exhibit.

  

  The two routers have had their startup configurations cleared and have been restarted. At a minimum, what must the administrator do to enable CDP to exchange information between R1 and R2?

  A. Configure the router with the cdp enable command.
  B. Enter no shutdown commands on the R1 and R2 fa0/1 interfaces.
  C. Configure IP addressing and no shutdown commands on both the R1 and R2 fa0/1 interfaces.
  D. Configure IP addressing and no shutdown commands on either of the R1 or R2 fa0/1 interfaces.
  B. Enter no shutdown commands on the R1 and R2 fa0/1 interfaces.

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  If the shut down commands are not entered, then CDP can exchange information between the two routers, else it would fail.

• Question 153:

  Which three statements are true about the operation of a full-duplex Ethernet network? (Choose three.)

  A. There are no collisions in full-duplex mode.
  B. A dedicated switch port is required for each full-duplex node.
  C. Ethernet hub ports are preconfigured for full-duplex mode.
  D. In a full-duplex environment, the host network card must check for the availability of the network media before transmitting.
  E. The host network card and the switch port must be capable of operating in full-duplex mode.
  A. There are no collisions in full-duplex mode.
  B. A dedicated switch port is required for each full-duplex node.
  E. The host network card and the switch port must be capable of operating in full-duplex mode.

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  Half-duplex Ethernet is defined in the original 802.3 Ethernet and Cisco says you only use one wire pair with a digital signal running in both directions on the wire. It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur. If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions. Half-duplex Ethernet--typically 10BaseT--is only about 30 to 40 percent efficient as Cisco sees it, because a large 10BaseT network will usually only give you 3- to 4Mbps--at most. Full-duplex Ethernet uses two pairs of wires, instead of one wire pair like half duplex. Also, full duplex uses a point-to-point connection between the transmitter of the transmitting device and the receiver of the receiving device, which means that with full-duplex data transfer, you get a faster data transfer compared to half duplex. And because the transmitted data is sent on a different set of wires than the received data, no collisions occur. The reason you don't need to worry about collisions is because now Full-duplex Ethernet is like a freeway with multiple lanes instead of the single-lane road provided by half duplex. Full- duplex Ethernet is supposed to offer 100 percent efficiency in both directions; this means you can get 20Mbps with a 10Mbps Ethernet running full duplex, or 200Mbps for FastEthernet.

• Question 154:

  A network administrator cannot connect to a remote router by using SSH. Part of the show interfaces command is shown.

  router#show interfaces

  Serial0/1/0 is up, line protocol is down

  At which OSI layer should the administrator begin troubleshooting?

  A. physical
  B. data link
  C. network
  D. transport
  B. data link

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  https://learningnetwork.cisco.com/thread/12389

  I think the indication here is "Serial 0 is up, line protocol is down". What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged is not a correct answer. If you check the output of your "show interface serial 0" command again, you should notice it as "Serial 0 is down, line protocol is down. Under the "show ip int brief" you should see status = down and protocol = down as opposed to up, down. Because you disconnected the cable, layer 1 will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a cable unplugged is not a correct answer to "Serial 0 is up, line protocol is down". Hope this helps.

  

• Question 155:

  Refer to the graphic.

  

  R1 is unable to establish an OSPF neighbor relationship with R3. What are possible reasons for this problem? (Choose two.)

  A. All of the routers need to be configured for backbone Area 1.
  B. R1 and R2 are the DR and BDR, so OSPF will not establish neighbor adjacency with R3.
  C. A static route has been configured from R1 to R3 and prevents the neighbor adjacency from being established.
  D. The hello and dead interval timers are not set to the same values on R1 and R3.
  E. EIGRP is also configured on these routers with a lower administrative distance.
  F. R1 and R3 are configured in different areas.
  D. The hello and dead interval timers are not set to the same values on R1 and R3.
  F. R1 and R3 are configured in different areas.

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  This question is to examine the conditions for OSPF to create neighborhood. So as to make the two routers become neighbors, each router must be matched with the following items:

  1.

  The area ID and its types;

  2.

  Hello and failure time interval timer;

  3.

  OSPF Password (Optional);

• Question 156:

  Which two statements describe the operation of the CSMA/CD access method? (Choose two.)

  A. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.
  B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
  C. The use of hubs to enlarge the size of collision domains is one way to improve the operation of the CSMA/CD access method.
  D. After a collision, the station that detected the collision has first priority to resend the lost data.
  E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.
  F. After a collision, all stations involved run an identical backoff algorithm and then synchronize with each other prior to transmitting data.
  B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
  E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.

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  Ethernet networking uses Carrier Sense Multiple Access with Collision Detect (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium. CSMA/CD was created to overcome the problem of those collisions that occur when packets are transmitted simultaneously from different nodes. And trust me, good collision management is crucial, because when a node transmits in a CSMA/CD network, all the other nodes on the network receive and examine that transmission. Only bridges and routers can effectively prevent a transmission from propagating throughout the entire network! So, how does the CSMA/CD protocol work? Like this: when a host wants to transmit over the network, it first checks for the presence of a digital signal on the wire. If all is clear (no other host is transmitting), the host will then proceed with its transmission. But it doesn't stop there. The transmitting host constantly monitors the wire to make sure no other hosts begin transmitting. If the host detects another signal on the wire, it sends out an extended jam signal that causes all nodes on the segment to stop sending data (think, busy signal). The nodes respond to that jam signal by waiting a while before attempting to transmit again. Backoff algorithms determine when the colliding stations can retransmit. If collisions keep occurring after 15 tries, the nodes attempting to transmit will then time out.

• Question 157:

  What happens when computers on a private network attempt to connect to the Internet through a Cisco router running PAT?

  A. The router uses the same IP address but a different TCP source port number for each connection.
  B. An IP address is assigned based on the priority of the computer requesting the connection.
  C. The router selects an address from a pool of one-to-one address mappings held in the lookup table.
  D. The router assigns a unique IP address from a pool of legally registered addresses for the duration of the connection.
  A. The router uses the same IP address but a different TCP source port number for each connection.

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  http://www.cisco.com/en/US/docs/security/asa/asa82/configuration/guide/nat_staticpat.html

  Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific port on a local address. That is, both the address and the port numbers are translated. Static PAT is the same as static NAT, except that it enables you to specify the protocol (TCP or UDP) and port for the real and mapped addresses. Static PAT enables you to identify the same mapped address across many different static statements, provided that the port is different for each statement. You cannot use the same mapped address for multiple static NAT statements. Port Address Translation makes the PC connect to the Internet but using different TCP source port.

• Question 158:

  Which of the following are types of flow control? (Choose three.)

  A. buffering
  B. cut-through
  C. windowing
  D. congestion avoidance
  E. load balancing
  A. buffering
  C. windowing
  D. congestion avoidance

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  http://www.info-it.net/cisco/ccna/exam-tips/flow-control.php During Transfer of data, a high speed computer is generating data traffic a lot faster than the network device can handle in transferring to destination, so single gateway or destination device cannot handle much amount of traffic that is called "Congestion". Buffering The Technie is used to control the data transfer when we have congestion, when a network device receive a data it stores in memory section and then transfer to next destination this process called "Buffering". Windowing Whereas Windowing is used for flow control by the Transport layer. Say the sender device is sending segments and the receiver device can accommodate only a fixed number of segments before it can accept more, the two devices negotiate the window size during the connection setup. This is done so that the sending device doesn't overflow the receiving device's buffer. Also the receiving device can send a single acknowledgement for the segments it has received instead of sending an acknowledgement after every segment received. Also, this window size is dynamic meaning, the devices can negotiate and change the window size in the middle of a session. So if initially the window size is three and the receiving device thinks that it can accept more number of segments in its buffer it can negotiate with the sending device and it increase it to say 5 for example. Windowing is used only by TCP since UDP doesn't use or allow flow control.

• Question 159:

  Scenario

  Refer to the topology. Your company has decided to connect the main office with three other remote branch offices using point-to-point serial links.

  You are required to troubleshoot and resolve OSPF neighbor adjacency issues between the main office and the routers located in the remote branch offices.

  

  

  

  

  

  An OSPF neighbor adjacency is not formed between R3 in the main office and R5 in the Branch2 office. What is causing the problem?

  A. There is an area ID mismatch.
  B. There is a PPP authentication issue; a password mismatch.
  C. There is an OSPF hello and dead interval mismatch.
  D. There is a missing network command in the OSPF process on R5.
  C. There is an OSPF hello and dead interval mismatch.

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  The "show ip ospf interface command on R3 and R5 shows that the hello and dead intervals do not match. They are 50 and 200 on R3 and 10 and 40 on R5.

  

• Question 160:

  Which of the following describe the process identifier that is used to run OSPF on a router? (Choose two)

  A. It is locally significant.
  B. It is globally significant.
  C. It is needed to identify a unique instance of an OSPF database.
  D. It is an optional parameter required only if multiple OSPF processes are running on the router.
  E. All routers in the same OSPF area must have the same process ID if they are to exchange routing information.
  A. It is locally significant.
  C. It is needed to identify a unique instance of an OSPF database.

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  https://learningnetwork.cisco.com/thread/6248

  They are locally significant only, and have no bearing on the structure of any OSPF packet or LSA update. So you can have a separate process-id on every single router in your network if you so desire!