Question 1

How many non-overlapping channels are available with the 802.11a wireless standard?

Accepted Answer

There are 12 non-overlapping channels available with the 802.11a wireless standard.
Key Takeaway: 802.11a has 12 non-overlapping channels, with a channel spacing of 20 MHz wide. 802.11a supports bandwidth up to 54 Mbps and signals in a regulated frequency spectrum around 5 GHz.

Question 2

Which of these protocols provides TCP/IP functions like IP addresses, subnet masks, default gateways, and DNS server information for hosts on a network?

Accepted Answer

DHCP provides TCP/IP functions like IP addresses, subnet masks, default gateways, and DNS server information for the hosts on a network.
Key Takeaway: DHCP is a protocol used by DHCP clients that dynamically distributes the IP address to the destination host. When a DHCP-configured host connects to a network, the DHCP client sends a broadcast query requesting necessary information from a DHCP server. The DHCP server manages a pool of IP addresses and information about client configuration parameters such as default gateway, domain name, the DNS servers, and other servers, such as time servers.

Question 3

Which one of the following protocols distributes information about the configuration of a new VLAN to the entire switched network?

Accepted Answer

VTP distributes information about the configuration of a new VLAN to the switched network.
Key Takeaway: VTP is a Cisco proprietary Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network. It reduces administration in a switched network. When a new VLAN is configured on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP carries VLAN information to all the switches in a VTP domain.

Question 4

David is a network administrator at his organization. He must use a routing protocol to connect the two autonomous systems as displayed in the figure. Which protocol should he choose?

Accepted Answer

BGP is the routing protocol used to connect the two autonomous systems.
Key Takeaway: Border Gateway Protocol is the routing protocol that maintains a table of IP networks or "prefixes," which designate network reachability among autonomous systems (AS). It is a path vector protocol. It does not use traditional Interior Gateway Protocol (IGP) metrics, but makes routing decisions based on path, network policies, and/or rule-sets.

Question 5

Which of the WAN data-link protocols below is used for out-of-band signaling?

Accepted Answer

LAPB is used for out-of-band signaling.
Key Takeaway: LAPD, or Link Access Procedure Balanced, implements the data link layer as defined in the X.25 protocol suite. It is a bit-oriented protocol derived from HDLC that ensures that frames are error-free and in the right sequence. It is used to manage communication and packet framing between data terminal equipment and the data circuit-terminating equipment devices in the X.25 protocol stack. LAPB sessions can be established by either the DTE or DCE. The station initiating the call is determined to be the primary and the responding station is the secondary.

Question 6

Which of the following switching modes provides the highest level of integrity and error-free transport, while sacrificing the speed of data transfer?

Accepted Answer

The store-and-forward switching mode provides the highest level of integrity and error-free transport.
Key Takeaway: The store-and-forward switching method copies the entire frame on the onboard buffers and does the cyclic redundancy check (CRC). The frame is discarded if it does not contain any errors. The switch looks up the destination address in its MAC address table and selects the outgoing interface. The frame is then forwarded to the destination.

Question 7

David is a network administrator in his organization. He has connected one of the company's servers directly to a Cisco switch through the Fa0/1 port. He wants to restrict access to other servers on this port. Which of the following should he do?

Accepted Answer

To be able to restrict other servers using the designated port, configure the MAC address of the server as a static entry associated with port Fa0/1 and reject traffic with a source MAC address other than that of the server.
Key Takeaway: Static entry is used to ensure that only a certain device, for example, a server, is plugged into a particular switch port. This is done by configuring the MAC address of the server as a static entry associated with the switch port. By doing this and specifying the MAC address of the server, he can block all incoming packets that do not have a source address specified.

Question 8

You want to prevent hosts from accessing the network if their MAC address is not authenticated to do so. Which of the following can be configured on a switch to prevent hosts with unauthorized MAC addresses from connecting to the network through a switch?

Accepted Answer

To restrict hosts from accessing the network if their MAC address is not approved, you should use the Port Security feature on the switch.
Key Takeaway: The Port Security feature on a switch stores the MAC address on a switch and allows only those MAC address to communicate on that port. If any other MAC address tries to communicate through the port, port security will disable the port. In the simplest form, Port Security requires an already-enabled switch port and the port-security Interface Mode command to be entered.

Question 9

Which of the following protocols provides best encryption in an IPsec VPN?

Accepted Answer

AES is the protocol that provides encryption in an IPsec VPN.
Key Takeaway: AES, or Advanced Encryption Standard, is an encryption scheme used as a replacement for DES. It is a symmetric-block cipher that can be used with 128, 192, and 256-bit keys. AES is the best among the ones specified, because it is both cryptographically strong and efficient to implement.

Question 10

Which of the following examines and recognizes different known attacks, as compared to a list of common attack signatures?

Accepted Answer

IDS examines and recognizes different known attacks, as compared to a list of common attack signatures.
Key Takeaway: IDS, or an Intrusion detection system, is a network security device that monitors network and system activities for malicious or unwanted behavior. Depending upon the approach and the goal of the IDS, the different types of IDS include Network based (NIDS) and Host based (HIDS) intrusion detection systems. The different types of IDS based upon how they function, are, Signature Based, Anomaly Based, and Passive IDS.

Question 11

During a data transfer from one PC to another, which of the following accurately describes the order of how data will be encapsulated?

Accepted Answer

The accurate order of how data is encapsulated is Data, Segment, Packet, Frame, and Bit.
Key Takeaway: Data is first broken down into segments in the Transport Layer. These segments are broken down into packets in the Network layer. The packets are broken down into frames in the datalink layer. Finally, the frames are broken down into bits in the physical layer and passed through the medium.

Question 12

Which of the following is a technology that Catalyst switches utilize to identify and prevent topology loops and ensure that data flows properly through a single network path?

Accepted Answer

STP, or Spanning Tree Protocol, identifies and prevents topology loops and ensures that data flows properly though a single network path.
Key Takeaway: Spanning Tree Protocol is a link management protocol that provides path redundancy and prevents undesirable loops on the network. Multiple active paths between stations cause loops in the network, which leads to duplication of messages. To provide path redundancy, STP defines a tree that spans all switches in an extended network. It forces certain redundant data paths into a standby or blocked state.

Question 13

Identify the component that must be elected before the Spanning Tree Protocol can converge in a switched LAN?

Accepted Answer

Before the STP can converge into a switched LAN, you must elect the root bridge.
Key Takeaway: The root switch in an STP is the logical center of the spanning-tree topology in a switched network. All paths that do not need to reach the root switch are placed in the backup mode.

Question 14

David is trying to troubleshoot an issue with his organization's frame relay network. He logs onto the remote router via a telnet session and issues the command "debug frame-relay lmi." He fails to see any output, even after a long time. Which of the following should he do to solve the issue?

Accepted Answer

To solve this issue, he must issue the terminal monitor command.
Key Takeaway: The terminal monitor command is used to display the debug command output and system error messages for the current terminal and session.

Question 15

Two computers are communicating using a TCP protocol. The receiving host has failed to receive all of the segments that should be acknowledged. Which of the following can the host do to improve the reliability of this communication session?

Accepted Answer

To improve the reliability of the communication session, you should decrease the window size.
Key Takeaway: The TCP window size specifies the amount of outstanding data a sender can send on a particular connection before it gets an acknowledgment back from the receiver. The primary reason for the window is congestion control. The buffer to fill up the received data may fill faster than the receiving TCP can empty it. When this occurs, the receiving device may need to adjust the window size to prevent the buffer from being overloaded. This is when the window will be resized.

Question 16

Dave is trying to telnet to a router at the address 200.124.35.2 from a host with an IP address 203.24.35.2. The telnet session does not initiate and he suspects an issue with the protocol stack. Which of the following commands should he use?

Accepted Answer

To verify the integrity of the protocol stack, use the ping 127.0.0.1 command.
Key Takeaway: 127.0.0.1 is known as the loopback address. When the ping 127.0.0.1 is executed, the host computer will send out four packets and will receive four packets in return, with a 0% loss report. This verifies that the network interface card is working. It also assures that the drivers for that device also work and that your computer's TCP/IP is functioning, as well.

Question 17

David is working as a network advisor at his organization. Of late, a number of users are complaining about slow network performance, intermittent connectivity, and connection loss. A show interface command output verifies that the Ethernet interface configured as 100 Mbps full-duplex has a series of collisions. Which of the following could be the most likely cause of this problem?

Accepted Answer

All these symptoms are due to a duplex mismatch.
Key Takeaway: Duplex mismatch is a condition where two connected devices operate in different duplex modes. Many times, we have a situation where one device operates in half-duplex, while the other one operates in full-duplex. This affects the network performance, making it slower and unreliable.

Question 18

The following shows the configuration files for routers A and B:hostname A hostname B! !Username B password king username A password king! !interface serial 0 interface serial 0ip address 14.4.4.8 255.255.0.0 ip address 12.3.6.3 255.255.0.0encapsulation ppp encapsulation pppclockrate 56000 ppp authentication chapIn this situation, if you enter the "show interface serial 0" command on router A, which of the following will be displayed?

Accepted Answer

The router A console shows that the Serial 0 is up and line protocol is up, too.
Key Takeaway: The possible cause of this message is that a loop exists in the circuit. The sequence number in the keep-alive packet changes to a random number when a loop is first detected. If the same random number is returned over the line, a loop exists. To fix this, you should check to see whether the DSU/CSU is configured in manual loopback mode and disable it. You can also try reseating the DSU/CSU.

Question 19

Dave is trying to add a new router on an OSPF network. The networks attached to the new router do not appear in the routing tables of the other OSPF routers. The new router's configuration is as follows:Router(config)# router ospf 66Router(config-if)# network 10.0.0.0 255.0.0.0 area 0Which of the following could most likely be the issue?

Accepted Answer

The network wildcard mask is configured incorrectly.
Key Takeaway: In an OSPF configuration, you can choose the interface that is participating in an OSPF network. It provides better control during configuration; wildcards tell the router what you are actually trying to advertise. In this case, the wild card should have been 0.255.255.255, rather than 255.0.0.0.

Question 20

Which of the following EIGRP commands can check the IP addresses of the adjacent neighbors and verify the EIGRP retransmit intervals and queue counts?

Accepted Answer

R1 #show ip eigrp neighbors command can check the IP addresses of the adjacent neighbors and verify the EIGRP retransmit intervals and queue counts.
Key Takeaway: Each router using EIGRP keeps state information about adjacent neighbors. When the router learns about newly-discovered neighbors, the address, and interface of the neighbor is recorded. This information is stored in the neighbor data structure. The neighbor table holds these entries. The neighbor table entry also includes information required by the reliable transport mechanism. This command is used to determine when neighbors become active and inactive.

Quiz 3: Networking