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Q21. - (Topic 4) 

What is the best practice when assigning IP addresses in a small office of six hosts? 

A. Use a DHCP server that is located at the headquarters. 

B. Use a DHCP server that is located at the branch office. 

C. Assign the addresses by using the local CDP protocol. 

D. Assign the addresses statically on each node. 

Answer:

Explanation: 

Its best to use static addressing scheme where the number of systems is manageable rather than using a dynamic method such as DHCP as it is easy to operate and manage. 


Q22. - (Topic 4) 

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. 

Answer:

Reference: 

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. 


Q23. - (Topic 2) 

Refer to the exhibit. 

The ports that are shown are the only active ports on the switch. The MAC address table is shown in its entirety. The Ethernet frame that is shown arrives at the switch. 

What two operations will the switch perform when it receives this frame? (Choose two.) 

A. The MAC address of 0000.00aa.aaaa will be added to the MAC address table. 

B. The MAC address of 0000.00dd.dddd will be added to the MAC address table. 

C. The frame will be forwarded out of port fa0/3 only. 

D. The frame will be forwarded out of fa0/1, fa0/2, and fa0/3. 

E. The frame will be forwarded out of all the active ports. 

Answer: A,D 

Explanation: 

If the switch already has the MAC address in its table for the destination, it will forward the frame directly to the destination port. If it was not already in its MAC table, then they frame would have been flooded out all ports except for the port that it came from. It will also add the MAC address of the source device to its MAC address table 


Q24. - (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. 


Q25. - (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 


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Q26. - (Topic 3) 

Which IOS command is used to initiate a login into a VTY port on a remote router? 

A. router# login 

B. router# telnet 

C. router# trace 

D. router# ping 

E. router(config)# line vty 0 5 

F. router(config-line)# login 

Answer:

Explanation: 

VTY ports are telnet ports hence command B will initiate login to the telnet port. 


Q27. - (Topic 7) 

What is the default lease time for a DHCP binding? 

A. 24 hours 

B. 12 hours 

C. 48 hours 

D. 36 hours 

Answer:

Explanation: By default, each IP address assigned by a DHCP Server comes with a one-day lease, which is the amount of time that the address is valid. To change the lease value for an IP address, use the following command in DHCP pool configuration mode: 


Q28. - (Topic 1) 

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

A. buffering 

B. cut-through 

C. windowing 

D. congestion avoidance 

E. load balancing 

Answer: A,C,D 

Explanation: 

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 increases it to say 5 for example. Windowing is used only by TCP since UDP doesn't use or allow flow control. 

Reference: http://www.info-it.net/cisco/ccna/exam-tips/flow-control.php 


Q29. - (Topic 3) 

Which of the following IP addresses are valid Class B host addresses if a default Class B mask is in use? (Choose two.) 

A. 10.6.8.35 

B. 133.6.5.4 

C. 192.168.5.9 

D. 127.0.0.1 

E. 190.6.5.4 

Answer: B,E 

Explanation: 

The IP addresses 133.6.5.4 and 190.6.5.4 are both valid Class B addresses when a default mask is in use. The Class B default mask is 255.255.0.0 and the range of valid addresses is 128.0.0.0-

191.255.255.255. 

The IP address 10.6.8.35 is a Class A address. The Class A default mask is 255.0.0.0 and 

the range of valid addresses is 1.0.0.0 - 127.255.255.255, with the exception of the range 

127.0.0.1 - 127.255.255.255, which is reserved and cannot be assigned. 

The IP address 192.168.5.9 is a Class C address. The Class C default mask is 

255.255.255.0 and the range of valid addresses is 192.0.0.0 - 223.255.255.255. 

The IP address 127.0.0.1 is a Class A address, but it comes from a reserved portion that 

cannot be assigned. 

The range 127.0.0.1 - 127.255.255.255 is used for diagnostics, and although any address 

in the range will work as a diagnostic address, 127.0.0.1 is known as the loopback address. 

If you can ping this address, or any address in the 127.0.0.1 - 127.255.255.255 range, then 

the NIC is working and TCP/IP is installed. The Class A default mask is 255.0.0.0 and the range of valid addresses is 1.0.0.0 - 127.255.255.255, with the exception of the range 

127.0.0.1 - 127.255.255.255, which is reserved and cannot be assigned. 


Q30. DRAG DROP - (Topic 1) 

On the left are various network protocols. On the right are the layers of the TCP/IP model. Assuming a reliable connection is required, move the protocols on the left to the TCP/IP layers on the right to show the proper encapsulation for an email message sent by a host on a LAN. (Not all options are used.) 

Answer: