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Cisco Interconnecting Cisco Networking Devices Part 1 (ICND1 v3.0) Certification Exam

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Cisco 100-105 Free Practice Questions

Q1. - (Topic 5) 

Refer to the exhibit. 

For security reasons, information about RTA, including platform and IP addresses, should not be accessible from the Internet. This information should, however, be accessible to devices on the internal networks of RTA. 

Which command or series of commands will accomplish these objectives? 

A. RTA(config)#no cdp run 

B. RTA(config)#no cdp enable 

C. RTA(config)#interface s0/0 RTA(config-if)#no cdp run 

D. RTA(config)#interface s0/0 RTA(config-if)#no cdp enable 

Answer:

Explanation: 

http://www.cisco.com/en/US/tech/tk962/technologies_tech_note09186a00801aa000.shtml# topicenab 

When CDP is enabled globally using the cdp run command, it is enabled by default on all supported interfaces (except for Frame Relay multipoint subinterfaces) to send and receive CDP information. You can disable CDP on an interface that supports CDP with the no cdp enable command. 

Router#show cdp neighbors 

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge S - Switch, H - Host, I - IGMP, r – Repeater 

Router# On this router, CDP is enabled on Serial 1 and Ethernet 0 interfaces. Disable CDP on the Serial 1 interface and verify if the neighbor device is discovered on the serial 1 interface, as this output shows: Router#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#interface s1 Router(config-if)#no cdp enable Router(config-if)# Z Router#4w5D. %SYS-5-CONFIG_I: Configured from console by console 

Q2. - (Topic 5) 

A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session? 

A. decrease the window size 

B. use a different source port for the session 

C. decrease the sequence number 

D. obtain a new IP address from the DHCP server 

E. start a new session using UDP 

Answer: A Explanation: 

The Window bit in the header determines the number of segments that can be sent at a time. This is done to avoid overwhelming the destination. At the start of the session the window in small but it increases over time. The destination host can also decrease the window to slow down the flow. Hence the window is called the sliding window. When the source has sent the number of segments allowed by the window, it cannot send any further segments till an acknowledgement is received from the destination. On networks with high error rates or issues, decreasing the window size can result in more reliable transmission, as the receiver will need to acknowledge fewer segments. With a large window size, the sender will need to resend all the frames if a single one is not received by the receiver. 

Q3. - (Topic 3) 

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

A. 192.168.4.61 

B. 192.168.4.63 

C. 192.168.4.67 

D. 192.168.4.125 

E. 192.168.4.128 

F. 192.168.4.132 

Answer: C,D 

Explanation: 

Increment: 64 (/26 = 11111111.11111111.11111111.11000000) 

The IP 192.168.4.0 belongs to class C. The default subnet mask of class C is /24 and it has 

been subnetted with a /26 mask so we have 2(26-24).= 22.= 4 sub-networks: 

1st subnet: 192.168.4.0 (to 192.168.4.63) 

2nd subnet: 192.168.4.64 (to 192.168.4.127) 

3rd subnet: 192.168.4.128 (to 192.168.4.191) 

4th subnet: 192.168.4.192 (to 192.168.4.225) 

In all the answers above, only answer C and D are in the same subnet. 

Therefore only IPs in this range can be assigned to hosts. 

Q4. - (Topic 3) 

Which characteristics are representative of a link-state routing protocol? (Choose three.) 

A. provides common view of entire topology 

B. exchanges routing tables with neighbors C. calculates shortest path 

D. utilizes event-triggered updates 

E. utilizes frequent periodic updates 

Answer: A,C,D 

Explanation: 

Each of routers running link-state routing protocol learns paths to all the destinations in its 

“area” so we can say although it is a bit unclear. 

Link-state routing protocols generate routing updates only (not the whole routing table) 

when a change occurs in the network topology so 

Link-state routing protocol like OSPF uses Dijkstra algorithm to calculate the shortest path -> . 

Unlike Distance vector routing protocol (which utilizes frequent periodic updates), link-state 

routing protocol utilizes event-triggered updates (only sends update when a change occurs) 

-> 

Q5. - (Topic 3) 

What does administrative distance refer to? 

A. the cost of a link between two neighboring routers 

B. the advertised cost to reach a network 

C. the cost to reach a network that is administratively set 

D. a measure of the trustworthiness of a routing information source 

Answer:

Reference: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml 

Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value. 

Administrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of the trustworthiness of the source of the routing information. The smaller the administrative distance value, the more reliable the protocol. 

Q6. CORRECT TEXT - (Topic 6) 

Answer: Router>enable 

Router#config terminal Router(config)#hostname Apopka 2) Enable-secret password (cisco10): Apopka(config)#enable secret cisco10 3) Set the console password to RouterPass: Apopka(config)#line console 0 Apopka(config-line)#password RouterPass Apopka(config-line)#login Apopka(config-line)#exit 4) Set the Telnet password to scan90: Apopka(config)#line vty 0 4 Apopka(config-line)#password scan90 Apopka(config-line)#login Apopka(config-line)#exit 5) Configure Ethernet interface (on the right) of router Apopka: The subnet mask of the Ethernet network 209.165.201.0 is 27. From this subnet mask, we can find out the increment by converting it into binary form, that is /27 = 1111 1111.1111 1111.1111 1111.1110 0000. Pay more attention to the last bit 1 because it tells us the increment, using the formula: Increment = 2place of the last bit 1 (starts counting from 0,from right to left), in this case increment = 25 = 32. Therefore: Increment: 32 Network address: 209.165.201.0 Broadcast address: 209.165.201.31 (because 209.165.201.32 is the second subnetwork, so the previous IP - 209.165.201.31 - is the broadcast address of the first subnet). -> The second assignable host address of this subnetwork is 209.165.201.2/27 Assign the second assignable host address to Fa0/0 interface of Apopka router: Apopka(config)#interface Fa0/0 Apopka(config-if)#ip address 209.165.201.2 255.255.255.224 Apopka(config-if)#no shutdown Apopka(config-if)#exit 6) Configure Serial interface (on the left) of router Apopka: Using the same method to find out the increment of the Serial network: Serial network 192.0.2.128/28: Increment: 16 (/28 = 1111 1111.1111 1111.1111 1111.1111 0000) Network address: 192.0.2.128 (because 8 * 16 = 128 so 192.0.2.128 is also the network address of this subnet) Broadcast address: 192.0.2.143 -> The last assignable host address in this subnet is 192.0.2.142/28. Assign the last assignable host address to S0/0/0 interface of Apopka router: Apopka(config)#interface S0/0/0 (or use interface S0/0 if not successful) Apopka(config-if)#ip address 192.0.2.142 255.255.255.240 Apopka(config-if)#no shutdown Apopka(config-if)#exit 7) Configure RIP v2 routing protocol: Apopka(config)#router rip Apopka(config-router)#version 2 Apopka(config-router)#network 209.165.201.0 Apopka(config-router)#network 192.0.2.128 Apopka(config-router)#end Save the configuration: Apopka#copy running-config startup-config Finally, you should use the ping command to verify all are working properly! 

Topic 7, Mix Questions 

Q7. - (Topic 7) 

Which option is the default switch port port-security violation mode? 

A. shutdown 

B. protect 

C. shutdown vlan 

D. restrict 

Answer:

Explanation: Shutdown—This mode is the default violation mode; when in this mode, the switch will automatically force the switchport into an error disabled (err-disable) state when a violation occurs. While in this state, the switchport forwards no traffic. The switchport can be brought out of this error disabled state by issuing the errdisable recovery cause CLI command or by disabling and reenabling the switchport. 

Shutdown VLAN—This mode mimics the behavior of the shutdown mode but limits the error disabled state the specific violating VLAN. 

Q8. - (Topic 1) 

Which statements are true regarding ICMP packets? (Choose two.) 

A. They acknowledge receipt of TCP segments. 

B. They guarantee datagram delivery. 

C. TRACERT uses ICMP packets. 

D. They are encapsulated within IP datagrams. 

E. They are encapsulated within UDP datagrams. 

Answer: C,D 

Explanation: 

Ping may be used to find out whether the local machines are connected to the network or whether a remote site is reachable. This tool is a common network tool for determining the network connectivity, which uses ICMP protocol instead of TCP/IP and UDP/IP. This protocol is usually associated with the network management tools, which provide network information to network administrators, such as ping and traceroute (the later also uses the UDP/IP protocol). ICMP is quite different from the TCP/IP and UDP/IP protocols. No source and destination ports are included in its packets. Therefore, usual packet-filtering rules for TCP/IP and UDP/IP are not applicable. Fortunately, a special "signature" known as the packet’s Message type is included for denoting the purposes of the ICMP packet. Most commonly used message types are namely, 0, 3, 4, 5, 8, 11, and 12 which represent echo reply, destination unreachable, source quench, redirect, echo request, time exceeded, and parameter problem respectively. In the ping service, after receiving the ICMP "echo request" packet from the source location, the destination 

Q9. - (Topic 3) 

Which two statements describe the process identifier that is used in the command to configure OSPF on a router? (Choose two.) 

Router(config)# router ospf 1 

A. All OSPF routers in an area must have the same process ID. 

B. Only one process number can be used on the same router. 

C. Different process identifiers can be used to run multiple OSPF processes 

D. The process number can be any number from 1 to 65,535. 

E. Hello packets are sent to each neighbor to determine the processor identifier. 

Answer: C,D 

Explanation: 

Multiple OSPF processes can be configured on a router using multiple process ID’s. 

The valid process ID’s are shown below: Edge-B(config)#router ospf <1-65535> Process ID 

Q10. - (Topic 3) 

Which router command will configure an interface with the IP address 10.10.80.1/19? 

A. router(config-if)# ip address 10.10.80.1/19 

B. router(config-if)# ip address 10.10.80.1 255.255.0.0 

C. router(config-if)# ip address 10.10.80.1 255.255.255.0 

D. router(config-if)# ip address 10.10.80.1 255.255.224.0 

E. router(config-if)# ip address 10.10.80.1 255.255.240.0 

F. router(config-if)# ip address 10.10.80.1 255.255.255.240 

Answer:

Explanation: 

255.255.224 equal /19 in CIDR format hence the answer 

Q11. - (Topic 5) 

Refer to the exhibit. 

A problem with network connectivity has been observed. It is suspected that the cable connected to switch port Fa0/9 on Switch1 is disconnected. What would be an effect of this cable being disconnected? 

A. Host B would not be able to access the server in VLAN9 until the cable is reconnected. 

B. Communication between VLAN3 and the other VLANs would be disabled. 

C. The transfer of files from Host B to the server in VLAN9 would be significantly slower. 

D. For less than a minute, Host B would not be able to access the server in VLAN9. Then normal network function would resume. 

Answer:

Explanation: 

Because Switch1 has multiple redundant links in this network, traffic would not work for less than a minute, and then it would get rerouted along the longer path to the host. The 1 minute outage would be the length of time it takes STP to converge. 

Q12. - (Topic 3) 

Refer to the exhibit. 

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

A. The loopback addresses are on different subnets. 

B. The values of the dead timers on the routers are different. 

C. Route summarization is enabled on both routers. 

D. The process identifier on router A is different than the process identifier on router B. 

Answer:

Explanation: 

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

Q13. - (Topic 1) 

Refer to the exhibit. 

Mary is sending an instant message to Robert. The message will be broken into a series of packets that will traverse all network devices. What addresses will populate these packets as they are forwarded from Router1 to Router2? 

A. Option A 

B. Option B 

C. Option C 

D. Option D 

E. Option E 

Answer:

Explanation: 

The Source and Destination IP address is not going to change. Host 1 IP address will stay 

as being the source IP and the Host 2 IP address will stay the destination IP address. 

Those two are not going to change. 

For the MAC address it is going to change each time it goes from one hope to another. 

(Except switches... they don't change anything) 

Frame leaving HOST 1 is going to have a source MAC of Host 1 and a destination MAC of 

Router 1. 

Router 1 is going to strip that info off and then will make the source MAC address of Router1's exiting interface, and making Router2's interface as the destination MAC address. Then the same will happen... Router2 is going to change the source/destination info to the source MAC being the Router2 interface that it is going out, and the destination will be Host2's MAC address. 

Q14. - (Topic 5) 

If a host experiences intermittent issues that relate to congestion within a network while remaining connected, what could cause congestion on this LAN? 

A. half-duplex operation 

B. broadcast storms 

C. network segmentation 

D. multicasting 

Answer:

Explanation: 

A broadcast storm can consume sufficient network resources so as to render the network unable to transport normal traffic. 

Topic 6, Simulation 

Q15. - (Topic 7) 

Which technology supports the stateless assignment of IPv6 addresses? 

A. DNS 

B. DHCPv6 

C. DHCP 

D. autoconfiguration 

Answer:

Explanation: DHCPv6 Technology Overview IPv6 Internet Address Assignment Overview 

IPv6 has been developed with Internet Address assignment dynamics in mind. Being aware that IPv6 Internet addresses are 128 bits in length and written in hexadecimals makes automation of address-assignment an important aspect within network design. These attributes make it inconvenient for a user to manually assign IPv6 addresses, as the format is not naturally intuitive to the human eye. To facilitate address assignment with little or no human intervention, several methods and technologies have been developed to automate the process of address and configuration parameter assignment to IPv6 hosts. The various IPv6 address assignment methods are as follows: 

1. 

Manual Assignment An IPv6 address can be statically configured by a human operator. However, manual assignment is quite open to errors and operational overhead due to the 128 bit length and hexadecimal attributes of the addresses, although for router interfaces and static network elements and resources this can be an appropriate solution. 

2. 

Stateless Address Autoconfiguration (RFC2462) Stateless Address Autoconfiguration (SLAAC) is one of the most convenient methods to assign Internet addresses to IPv6 nodes. This method does not require any human intervention at all from an IPv6 user. If one wants to use IPv6 SLAAC on an IPv6 node, it is important that this IPv6 node is connected to a network with at least one IPv6 router connected. This router is configured by the network administrator and sends out Router Advertisement announcements onto the link. These announcements can allow the on-link connected IPv6 nodes to configure themselves with IPv6 address and routing parameters, as specified in RFC2462, without further human intervention. 

3. 

Stateful DHCPv6 The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) has been standardized by the IETF through RFC3315. DHCPv6 enables DHCP servers to pass configuration parameters, 

such as IPv6 network addresses, to IPv6 nodes. It offers the capability of automatic allocation of reusable network addresses and additional configuration flexibility. This protocol is a stateful counterpart to "IPv6 Stateless Address Autoconfiguration" (RFC 2462), and can be used separately, or in addition to the stateless autoconfiguration to obtain configuration parameters. 

4. 

DHCPv6-PD DHCPv6 Prefix Delegation (DHCPv6-PD) is an extension to DHCPv6, and is specified in RFC3633. Classical DHCPv6 is typically focused upon parameter assignment from a DHCPv6 server to an IPv6 host running a DHCPv6 protocol stack. A practical example would be the stateful address assignment of "2001:db8::1" from a DHCPv6 server to a DHCPv6 client. DHCPv6-PD however is aimed at assigning complete subnets and other network and interface parameters from a DHCPv6-PD server to a DHCPv6-PD client. This means that instead of a single address assignment, DHCPv6-PD will assign a set of IPv6 "subnets". An example could be the assignment of "2001:db8::/60" from a DHCPv6-PD server to a DHCPv6-PD client. This will allow the DHCPv6-PD client (often a CPE device) to segment the received address IPv6 address space, and assign it dynamically to its IPv6 enabled.interfaces. 

5.

 Stateless DHCPv6 Stateless DHCPv6 is a combination of "stateless Address Autoconfiguration" and "Dynamic Host Configuration Protocol for IPv6" and is specified by RFC3736. When using stateless-DHCPv6, a device will use Stateless Address Auto-Configuration (SLAAC) to assign one or more IPv6 addresses to an interface, while it utilizes DHCPv6 to receive "additional parameters" which may not be available through SLAAC. For example, additional parameters could include information such as DNS or NTP server addresses, and are provided in a stateless manner by DHCPv6. Using stateless DHCPv6 means that the DHCPv6 server does not need to keep track of any state of assigned IPv6 addresses, and there is no need for state refreshment as result. On network media supporting a large number of hosts associated to a single DHCPv6 server, this could mean a significant reduction in DHCPv6 messages due to the reduced need for address state refreshments. From Cisco IOS 12.4(15)T onwards the client can also receive timing information, in addition to the "additional parameters" through DHCPv6. This timing information provides an indication to a host when it should refresh its DHCPv6 configuration data. This behavior (RFC4242) is particularly useful in unstable environments where changes are likely to occur. 

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