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Q11. - (Topic 3) 

Which command is used to display the collection of OSPF link states? 

A. show ip ospf link-state 

B. show ip ospf lsa database 

C. show ip ospf neighbors 

D. show ip ospf database 

Answer:

Explanation: 

The “show ip ospf database” command displays the link states. Here is an example: 

Here is the lsa database on R2. 

R2#show ip ospf database 

OSPF Router with ID (2.2.2.2) (Process ID 1) 

Router Link States (Area 0) 

Link ID ADV Router Age Seq# Checksum Link count 

2.2.2.2 2.2.2.2 793 0x80000003 0x004F85 2 

10.4.4.4 10.4.4.4 776 0x80000004 0x005643 1 

111.111.111.111 111.111.111.111 755 0x80000005 0x0059CA 2 

133.133.133.133 133.133.133.133 775 0x80000005 0x00B5B1 2 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum10.1.1.1 111.111.111.111 794 0x80000001 0x001E8B 

10.2.2.3 133.133.133.133 812 0x80000001 0x004BA9 

10.4.4.1 111.111.111.111 755 0x80000001 0x007F16 

10.4.4.3 133.133.133.133 775 0x80000001 0x00C31F 


Q12. - (Topic 5) 

Including the address on the Routed Ethernet interface, how many hosts can have IP addresses on the LAN to which Routed is connected? 

A. 6 

B. 30 

C. 62 

D. 126 

Answer:

Explanation: 

This is a /29 address, so there are 6 usable IP’s on this subnet. 


Q13. - (Topic 5) 

From which of the following attacks can Message Authentication Code (MAC) shield your network? 

A. DoS 

B. DDoS 

C. spoofing 

D. SYN floods 

Answer:

Explanation: 

Message Authentication Code (MAC) can shield your network from spoofing attacks. Spoofing, also known as masquerading, is a popular trick in which an attacker intercepts a network packet, replaces the source address of the packets header with the address of the authorized host, and reinserts fake information which is sent to the receiver. This type of attack involves modifying packet contents. MAC can prevent this type of attack and ensure data integrity by ensuring that no data has changed. MAC also protects against frequency analysis, sequence manipulation, and ciphertext-only attacks. MAC is a secure message digest that requires a secret key shared by the sender and receiver, making it impossible for sniffers to change both the data and the MAC as the receiver can detect the changes. A denial-of-service (DoS) attack floods the target system with unwanted requests, causing the loss of service to users. One form of this attack generates a flood of packets requesting a TCP connection with the target, tying up all resources and making the target unable to service other requests. MAC does not prevent DoS attacks. Stateful packet filtering is the most common defense against a DoS attack. A Distributed Denial of Service attack (DDoS) occurs when multiple systems are used to flood the network and tax the resources of the target system. Various intrusion detection systems, utilizing stateful packet filtering, can protect against DDoS attacks. In a SYN flood attack, the attacker floods the target with spoofed IP packets and causes it to either freeze or crash. A SYN flood attack is a type of denial of service attack that exploits the buffers of a device that accept incoming connections and therefore cannot be prevented by MAC. Common defenses against a SYN flood attack include filtering, reducing the SYN-RECEIVED timer, and implementing SYN cache or SYN cookies. 


Q14. - (Topic 7) 

Which destination IP address can a host use to send one message to multiple devices across different subnets? 

A. 172.20.1.0 

B. 127.0.0.1 

C. 192.168.0.119 

D. 239.255.0.1 

Answer:

Explanation: Multicast is a networking protocol where one host can send a message to a special multicast IP address and one or more network devices can listen for and receive 

those messages. Multicast works by taking advantage of the existing IPv4 networking infrastructure, and it does so in something of a weird fashion. As you read, keep in mind that things are a little confusing because multicast was "shoe-horned" in to an existing technology. For the rest of this article, let's use the multicast IP address of 239.255.0.1. We'll not worry about port numbers yet, but make a mental note that they are used in multicast. We'll discuss that later. 


Q15. - (Topic 1) 

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. 

Answer: B,E 

Explanation: 

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. 


Q16. - (Topic 5) 

Refer to the exhibit. 

A TFTP server has recently been installed in the Atlanta office. The network administrator is located in the NY office and has made a console connection to the NY router. After establishing the connection they are unable to backup the configuration file and IOS of the NY router to the TFTP server. What is the cause of this problem? 

A. The NY router has an incorrect subnet mask. 

B. The TFTP server has an incorrect IP address. 

C. The TFTP server has an incorrect subnet mask. 

D. The network administrator computer has an incorrect IP address. 

Answer:

Explanation: 

The TFTP server is using a mask of 255.255.255.240 (/28) while the router is configured with a /29. Because of this, the Atlanta router does not see the TFTP server as being in the same subnet. 


Q17. - (Topic 4) 

Refer to the exhibit. 

A company wants to use NAT in the network shown. Which commands will apply the NAT configuration to the proper interfaces? (Choose two.) 

A. R1(config)# interface serial0/1 R1(config-if)# ip nat inside 

B. R1(config)# interface serial0/1 R1(config-if)# ip nat outside 

C. R1(config)# interface fastethernet0/0 R1(config-if)# ip nat inside 

D. R1(config)# interface fastethernet0/0 R1(config-if)# ip nat outside 

E. R1(config)# interface serial0/1 R1(config-if)# ip nat outside source pool 200.2.2.18 255.255.255.252 

F. R1(config)# interface fastethernet0/0 R1(config-if)# ip nat inside source 10.10.0.0 255.255.255.0 

Answer: B,C 

Explanation: 

For NAT, you need to define which interfaces are inside and which are outside. The outside interface is the one that connects to the external network, and the one that will be used for translating addresses. The inside interface is for the internal network, and defines the network IP addresses that will get translated to the one specified in the outside network. 


Q18. - (Topic 1) 

On a Cisco switch, which protocol determines if an attached VoIP phone is from Cisco or from another vendor? 

A. RTP 

B. TCP 

C. CDP 

D. UDP 

Answer:

Explanation: 

The Cisco Unified IP Phone uses CDP to communicate information such as auxiliary VLAN ID, per port power management details, and Quality of Service (QoS) configuration information with the Cisco Catalyst switch. Cisco Discovery Protocol (CDP) is a proprietary protocol designed by Cisco to help administrators collect information about both locally attached and remote devices. By using CDP, you can gather hardware and protocol information about neighbor devices, which is useful info for troubleshooting the network. CDP messages are generated every 60 seconds as multicast messages on each of its active interfaces. The information shared in a CDP packet about a Cisco device includes the following: Name of the device configured with the hostname command IOS software version Hardware capabilities, such as routing, switching, and/or bridging Hardware platform, such as 2600, 2950, or 1900 The layer-3 address(es) of the device The interface the CDP update was generated on 

Reference: http://computernetworkingnotes.com/cisco-devices-administration-and-configuration/cisco-discoveryprotocol.html 


Q19. - (Topic 5) 

Refer to the exhibit. 

Serial 0/0 does not respond to a ping request from a host on the FastEthernet 0/0 LAN. How can this problem be corrected? 

A. Enable the Serial 0/0 interface. 

B. Correct the IP address for Serial 0/0. 

C. Correct the IP address for FastEthernet 0/0 

D. Change the encapsulation type on Serial 0/0 

E. Enable autoconfiguration on the Serial 0/0 interface 

Answer:

Explanation: 

Serial 0/0 interface is administratively down therefore, you will have to run the "no shutdown" command to enable the interface for data. 


Q20. - (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