Question 1

Which of the following topologies is used by nodes on a 10BASE-T Ethernet network to connect to a central hub or repeater?

Accepted Answer

A star topology has a central hub connecting the stations around it.
Key Takeaway: Star topology is the most common type of network topology used in homes and offices. A star topology has a central connection point called the hub, which is a computer hub or a switch. The best advantage of star topology is that a failure in cabling affects only one computer and not the entire network. In a mesh topology, every workstation has a connection to every other component of the network. A bus topology uses one cable as a main trunk to connect all of the systems together. In ring topology, all computers are connected via a cable that loops in a ring or circle.

Question 2

Which of the following topologies is the most difficult to manage, and is the least easily scalable?

Accepted Answer

The Mesh topology is the most difficult to manage and is the least easily scalable.
Key Takeaway: With the mesh topology, each node is connected to every other node in the network. Because of this, with each new node that is to be added, there are an increasing number of connections that must be added as well. For example, if we have 4 computers in a mesh topology configuration, then we have 12 connections. When we add a 5th computer the number of connections goes up to 20, with a 6ththe number increases to 30. This also leads to difficulty in management, especially compared to the ring, tree, and bus topologies which are relatively easy to manage.

Question 3

Tara, a LAN administrator, is tasked with designing a communications datacenter on a very tight budget. What will allow Tara to implement 10 Gigabit speeds, while still maintaining the lowest cost for cabling?

Accepted Answer

Installing 10GbaseT will maintain the lowest cost for cabling in the datacenter.
Key Takeaway: 10GbaseT cabling is the standard for 10 Gigabit Ethernet over copper cabling. Specifically the 10GbaseT is much less expensive than 10GbaseSR, which refers to fiber that runs at the same speed. The "10base" standards refer to the 802.3 Ethernet standard set where the first part refers to the speed of the network media, the word refers to either baseband or broadband transmission, and the last part refers to a code that relates to either copper or fiber. For instance, 10BaseT is 10Mb copper (twisted pair) cable. Cat5e is not capable of reaching 10 Gigabit speeds and 10GbaseF is not an accurate term.

Question 4

In which network topology does a node communicate only with its upstream and downstream neighbors?

Accepted Answer

In a Ring topology, a node can communicate only with its upstream and downstream neighbors.
Key Takeaway: With the Ring topology, the nodes in the network are arranged in a circular format, similar to a ring. Each node can only communicate with the nodes directly next to it. Those nodes are called the "upstream" and "downstream" nodes. The positive aspect of this type of network are that when something goes wrong, it is immediately evident. However, this is also one of the bad things about this type of topology; if one node should fail, the entire network also goes down. Also, this type of network is not very scalable. If another computer is to be added, it must go in between two already configured devices. And those two devices will also need to be reconfigured to communicate with the new device. Due to the disadvantages of ring topology, it is rarely used in networks today.

Question 5

Without the use of a repeater or other similar device, what is the maximum distance a technician can run a 1000BaseT cable segment and still maintain the rated speeds?

Accepted Answer

The maximum distance a technician can run a 1000BaseT cable segment and still maintain the rated speeds is 100 meters, or 328 feet.
Key Takeaway: 1000BaseT cable is another way to describe Cat5 or better cable that can reach 1000Mb speeds. Cat5, Cat5e, Cat6, Cat6a, and even Cat7 all have a specified distance of 100 meters.

Question 6

If Tony, a network technician, has a cable with one end of the cable wired with the following pin configuration:
Orange-White/Orange/Green-White/Blue/Blue-White/Green/Brown-White/Brown
And the other end of the cable wired with the following configuration:
Green-White/Green/Orange-White/Blue/Blue-White/Orange /Brown-White/Brown
What kind of cable does Tim the technician have?

Accepted Answer

Given the pin configuration, Tim the technician has a crossover cable.
Key Takeaway: TIA/EIA has outlined standards for the pin out of networking cable for use in Local Area Networks. Two of the standards are the 568/A and the 568/B. The 568/A standard has the cable pin out beginning with Green-White/Green in the 1 and 2 pin slots of the RJ-45 cable. The 568/B standard has Orange-White/Orange in those pins. By creating a cable with one end having the 568/A standard, and the other end having the 568/B standard, this enables devices of the same type to be connected together such as a computer to a computer, or a switch to a switch. This means that the 1 and 2 pins are switched with the 3 and 6 pins.

Question 7

The IEEE has specified which of the following standards for wired Ethernet and further defines the LAN access method as CSMA/CD?

Accepted Answer

IEEE has specified the 802.3 standard for wired Ethernet and further defines the LAN access method as CSMA/CD.
Key Takeaway: The IEEE has established the 802.x family of standards that govern the implementation and configuration of local area networks and metropolitan area networks. The 802.15 standard is defined for Wireless Personal Area Networks, or WPANs. The 802.11 specification defines the Wireless Local Area Network or WLAN configurations and requirements. The 802.13 is unused at this time.

Question 8

What kinds of devices can determine the size of a broadcast domain?

Accepted Answer

Routers can determine the size of a broadcast domain.
Key Takeaway: A network where any node can communicate directly with any other node without having to go through a central routing device is considered a broadcast domain. As switches can only route traffic to devices on the same segment, they effectively would not be able to determine the size of a broadcast domain. However, routers can route traffic between segments and even LANs. Because of this, the router is the device that can be used to specify how large or small the broadcast domain will be.

Question 9

Via what media access method are devices assigned a time slot where they will have exclusive access to transmit data?

Accepted Answer

Time Division Multiplexing is the media access method where devices are assigned a time slot where they will have exclusive access to transmit data, though only during that period of time.
Key Takeaway: TDM is one of two media access methods that use multiplexing which is a central device that combines signals from multiple devices and transmits the combined signal across the medium. The other is FDM, or Frequency Division Multiplexing. TDM will use specified time slots designated for each device to use and FDM will allocate a specific frequency, or channel for each device. TDM will combine multiple baseband (digital) signals, whereas FDM will combine multiple broadband (analog) signals.

Question 10

Of the following Ethernet technology types, which will allow for the longest distance between transmitting devices?

Accepted Answer

10BaseF will allow for the longest distance between transmitting devices.
Key Takeaway: The 1000BaseCX is an Ethernet standard that utilizes shielded coaxial cable and is only rated for a maximum of 25 meters in length. The 100BaseTX utilizes Cat5 unshielded twisted pair and has a maximum rated cable length of 100 meters. While the data rate is the highest with the 10GbaseSR, which is multimode fiber, it is only rated for a maximum of 300 meters in cable length. Finally the 10BaseF is also fiber, but is rated for a maximum of about 2000 meters making it the longest out of the choices given.

Question 11

Alex the network administrator would like to increase throughput on the data link layer in the easiest manner possible. Which of the following will allow Alex to do this with the least amount of configuration?

Accepted Answer

NIC bonding will allow Alex to increase throughput on the data link layer in the easiest manner possible with the least configuration.
Key Takeaway: NIC bonding, also called channel bonding or NIC teaming is the process of assigning multiple interfaces (NICS) to a single MAC address. This will effectively increase the throughput at the data link layer by using channels to bind. Another method similar in implementation is called "trunking" which is the process of combining multiple links to increase bandwidth.

Question 12

Jack has accidentally messed up his wireless configuration. He has increased the value of the beacon interval from 10 ms to 20 ms. How could this affect the chances of unknown users connecting to his wireless network?

Accepted Answer

If the beacon interval is increased, the chance of Jack's network being detected by an unknown user decreases.
Key Takeaway: Beacon interval in a wireless network is the frequency at which the SSID broadcasts are sent out. Increasing the time interval between two successive broadcasts decreases the frequency. Hence, fewer broadcast messages go out in the open. Therefore, the chance of Jack's network being detected is significantly reduced.

Question 13

Bob, a new network consultant, is helping a business with their website updates. The firewall is in default deny mode, so he opens up port 21 to allow for FTP access to the webserver from the Internet. However, FTP still does not work. He notices that clients can connect, but cannot transfer any data. Why does FTP still not work?

Accepted Answer

FTP utilizes two TCP ports, 20 and 21. Port 21 is the control port that authenticates users and issues commands. Port 20 is the port on which the data is actually transferred.
Key Takeaway: FTP is a session oriented protocol and therefore uses TCP. TFTP uses UDP and is therefore connectionless and a lot less reliable. FTP always uses two ports. These ports are generally 20 and 21. Port 21 is the control channel responsible for authentication, issuing commands, and other administrative activities. Port 20 is generally the port on which the data is transferred. In passive mode, the server can negotiate another port other than 20 for data transfer.

Question 14

Bruce is a new network consultant and is designing a new network for a small business. Bruce sees that the business will have a mail server behind a firewall. What port needs to be open on the firewall for the server to send and receive email outside the local network?

Accepted Answer

Mail servers communicate using SMTP, which in turn uses port 25.
Key Takeaway: SMTP is the protocol used by mail servers to send and receive mail. SMTP stands for Simple Mail Transport Protocol and uses port 25 by default. Port 110 is used by POP3 servers for clients to retrieve mail, and port 3389 is for Microsoft remote desktop protocol.

Question 15

Jack is hosting a web site on his server. He has enabled a paid service on his web site and wants to use his server to make financial transactions. Which feature should he enable?

Accepted Answer

He should enable the HTTP Secure or HTTPS feature on his web server. This creates a secure channel over an insecure network and ensures reasonable protection from eavesdroppers and man-in-the-middle attacks, if adequate cipher suites are used and the server certificate is verified and trusted.
Key Takeaway: Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer Protocol combined with the SSL/TLS protocol to provide encryption and secure identification of the server. HTTPS connections are often used for payment transactions on the World Wide Web and for sensitive transactions in corporate information systems.

Question 16

The remote support team at an organization is having problems connecting to their client's computers using a remote desktop connection. All other network services are working fine. Which of the following could be a possible reason for this?

Accepted Answer

Microsoft Remote Desktop Protocol, or RDP, operates on port 3389. Port 3389 is not generally open by default on most firewalls.
Key Takeaway: RDP is the protocol used for Microsoft's Remote Desktop and operates on IP port 3389. RDP is secure because it encrypts the data in transfers once the user has logged into the session. This makes it fairly unsusceptible to man in the middle attacks, and further makes the use of SSL or TLS superfluous for remote access to a Windows desktop.

Question 17

Jack has not logged in to his e-mail account for a couple of weeks. Now, after entering his name and password, he receives an error message indicating that the username or password is invalid. What can he infer from this error message?

Accepted Answer

The fact that the user is getting an invalid message proves that the physical layer is working properly.
Key Takeaway: Password Authentication Protocol (PAP) is a simple authentication protocol used to authenticate a user to a network access server used by Internet service providers. Authentication is a process of validating a user before allowing them access to server resources. If the server is sending a message stating that the username and password is invalid, it proves that the physical layer as well as layers 2, 3, and 4 are working since the authentication is taking place.

Question 18

John is trying to install an application on his office desktop. He was able to install the software on his home PC (not connected to the Internet), which is identical to his office PC, but the application will not install on his office desktop. What could be stopping him from installing the application?

Accepted Answer

oIn this case, a software restriction policy setup by the IT team is not allowing him to install the applications on his office computer.
Key Takeaway: To help protect the network computers from both hostile code and unknown or unsupported software, organizations implement software restriction policies as part of their overall security strategy. It is done by determining which software is safe to run and which is not, and not allowing the unsafe software to be installed on the computer.

Question 19

John is a security advisor at his organization. He is asked to make sure that no visitors in the organization are able to connect their laptop computers to the network. Which of these features of a switch can he implement?

Accepted Answer

Port authentication is an important feature of the switch that allows the administrator to associate the MAC address of the system that will connect to the port.
Key Takeaway: IEEE 802.1X is an IEEE Standard for port-based Network Access Control using port authentication mechanisms. It provides an authentication mechanism to devices wishing to attach to a LAN, either establishing a point-to-point connection or preventing it if authentication fails. It is used for most wireless 802.11 access points and is based on the Extensible Authentication Protocol (EAP).

Question 20

Jack is fooled by a person who introduces himself as new IT staff in his organization. On the person's request, Jack reveals the web server login details. Later he comes to know that the person was a fraud and confidential data has been stolen from the web server. What kind of attack has Jack encountered?

Accepted Answer

Jack has encountered a Social Engineering attack.
Key Takeaway: Social Engineering is the act of manipulating people into performing actions or divulging confidential information. While similar to a confidence trick or simple fraud, the term typically applies to trickery or deception for the purpose of information gathering or computer system access. In most cases, the attacker never comes face-to-face with the victim. Man in the middle, Eavesdropping, and Smurf attacks are more technical ways of hacking a network or a system.

Quiz 23: Media Topologies