Term
| __________ is a reference model used to define how data communications occur on computer networks. |
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Definition
Open Systems Interconnection reference model (OSI)
The OSI model was created as a set of seven layers, each of which houses different protocols within one of several protocol suites, the most common of which is TCP/IP. The OSI model categorizes how TCP/IP transactions occur. It is invaluable when it comes to installing, configuring, maintaining, and, especially, troubleshooting networks. |
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Term
| What are the 7 Layers of the OSI model |
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Definition
Layer 1 - Physical
Layer 2 - Data Link
Layer 3 - Network
Layer 4 - Transport
Layer 5 - Session
Layer 6 - Presentation
Layer 7 - Application
Mnemonic - Please Do Not Throw Sausage Pizzas Away |
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Term
| Layer 1: Physical layer: This is the physical and electrical medium for data transfer. It includes but is not limited to cables, jacks, patch panels, punch blocks, hubs, and multistation access units (MAUs). It is also known as the physical plant. If you can touch it, it is part of the Physical layer.
The unit of measurement used on this layer is bits.
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Definition
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Term
| Layer 2: Data Link layer: This layer establishes, maintains, and decides how transfer is accomplished over the Physical layer. Devices that exist on the DLL are network interface cards, bridges, WAP, layer 2 switches and network adapters. Just about any device that makes a physical connection to the network and can move data is on the Data Link layer.
The unit of measurement used on this layer is frames.
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Definition
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Term
| Layer 3: Network layer: The Network layer is dedicated to routing and switching information between different networks, LANs, or internetworks. This can be on the LAN or WAN. Devices that exist on the Network layer are routers and IP switches. Now we are getting into the logical addressing of hosts.
Now you can see that a typical computer really has two addresses: a physical or hardware‐based address, such as a MAC address, and a logical or software‐based address, such as an IP address. Part of the trick in networking is to make sure the two get along together!
The unit of measurement used on this layer is packets.
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Definition
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Term
| Layer 4: Transport layer: This layer ensures error‐free transmission between hosts through logical addressing. Therefore, it manages the transmission of messages through Layers 1 through 3. The protocols that are categorized by this layer break up messages, send them through the subnet, and ensure correct reassembly at the receiving end, making sure there are no duplicates or lost messages. This layer contains both connection‐oriented and connectionless systems. Inbound and outbound ports are controlled by this layer. When you think ports, think the Transport layer.
The unit of measurement used on this layer is sometimes referred to as segments, or messages. All layers above this use the terms data and messages.
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Definition
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Term
| Layer 5: Session layer: This layer governs the establishment, termination, and synchronization of sessions within the OS over the network and between hosts-—for example, when you log on and log off. It is the layer that controls the name and address database for the OS or NOS. NetBIOS (Network Basic Input/Output System) works on this layer. |
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Definition
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Term
| Layer 6: Presentation layer: This layer translates the data format from sender to receiver in the various operating systems that may be used. Concepts include code conversion, data compression, and file encryption. Redirectors work on this layer, for example, mapped network drives that enable a computer to access file shares on a remote computer. |
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Definition
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Term
| Layer 7: Application layer: This is where message creation—and, therefore, packet creation—begins. DB access is on this level. End‐user protocols, such as FTP, SMTP, Telnet, and RAS, work at this layer. This layer is not the application itself, but the protocols that are initiated by this layer. |
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Definition
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Term
| _________ is the most common type of switch that is used on a LAN. They are hardware based and they use the MAC address of each host computer’s network adapter when deciding where to direct frames of data; every port on the switch is mapped to the specific MAC address of the computer that physically connects to it. |
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Definition
Layer 2 Switch
Layer 2 Switches do not normally modify frames as they pass through the switch. Can also allow for a VLAN. |
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Term
| __________ determines paths for data using logical addressing (IP addresses) instead of physical addressing (MAC addresses), they are very similar to routers. Can be managed by utilizing the Simple Network Management Protocol (SNMP). |
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Definition
Layer 3 Switch
Layer 3 switches forward packets, whereas Layer 2 forward frames. |
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Term
| __________ switches are the least expensive and are used in homes and Small Office/Home Office environments. You just connect AC power to the switch and connect your network devices. |
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Definition
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Term
| __________ switches include more advanced features, including supporting Spanning Tree Protocol, port mirroring, setting port bandwidth, and creating and modifying virtual LANs. |
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Definition
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Term
| Ports in the 0-1023 range are known as _________, and defines commonly used protocols; FTP, SMTP, and HTTP are some examples. |
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Definition
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Term
| Ports above 29,152 are known as __________. |
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Definition
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Term
What ports do the following use:
1. FTP
2. Telnet
3. SMTP
4. HTTP
5. POP3 |
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Definition
1. File Transfer Protocol 21
2. TErminaL NETwork -23
3. Simple Mail Transfer Protocol -25
4. Hypertext Transfer Protocol -80
5. Post Office Protocol Version 3 -110 |
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Term
| Switches reside on the Network layer. A Layer 3 switch differs from a Layer 2 switch in that it determines paths for data using logical addressing (IP addresses) instead of physical addressing (MAC addresses). Layer 3 switches are very similar to routers |
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Definition
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Term
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Definition
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Term
| What are the Layers of the TCP model |
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Definition
Layer 1: Data Link layer (aka Link layer)
Layer 2: Network layer (aka Internet layer)
Layer 3: Transport layer
Layer 4: Application layer - Comprises the OSI Application, Presentation and Session Layers. |
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Term
| TCP/IP protocol that is connection-oriented |
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Definition
Transmission Control Protocol (TCP)
Example would be a web browser. Using TCP ensures that data gets to its final destination. If a packet is lost along the way, it is resent until the destination computer acknowledges delivery or ends the session |
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Term
| TCP/IP protocol that is connectionless |
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Definition
User Datagram Protocol (UDP)
Example would be streaming media. But with streaming media, we are either watching or listening in real time. So, if a packet is lost, we don’t really care because that time frame of the video or music has already passed. |
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Term
Which layer in the OSI model is used to verify that data was delivered without error?
Select one:
A. Physical
B. Data Link
C. Network
D. Transport |
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Definition
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Term
Which layer in the OSI model do MAC addresses and switches use?
Select one:
A. Physical
B. Data Link
C. Network
D. Transport |
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Definition
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Term
Which layer of the OSI model includes VLANs?
Select one:
A. Physical
B. Data Link
C. Network
D. Transpor |
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Definition
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Term
Which layer in the OSI model covers routing between networks?
Select one:
A. Physical
B. Data Link
C. Network
D. Transpor |
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Definition
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Term
How many layers does the TCP/IP model have?
Select one:
A. 3
B. 4
C. 6
D. 7 |
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Definition
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Term
How many layers are incorporated in the OSI model communications subnetwork?
A. 2
B. 7
C. 3
D. 4 |
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Definition
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Term
Which of the following layers deals with the serial transfer of data?
A. Physical
B. Data Link
C. Network
D. Session |
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Definition
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Term
A problem is suspected with a computer’s network adapter and its ability to send the correct frames of data that correspond with the network architecture used by the rest of the computers. Which layer should be used as a troubleshooting starting point?
A. Physical
B. Data Link
C. Network
D. Transport |
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Definition
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Term
A director has given permission to access his computer. To find out the MAC address of the director’s computer, the Command Prompt application is accessed. Which command should be used to see the MAC address?
A. ipconfig
B. ipconfig /all
C. arp
D. netstat ‐an |
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Definition
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Term
Which of the following commands should be used to view all of the MAC addresses of computers that a particular user’s computer has connected to in the recent past?
A. ping 127.0.0.1
B. netstat ‐a
C. arp ‐a
D. arp ‐s |
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Definition
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Term
| Ports 1024–49,151 are ports used by vendors for proprietary applications. They are known as __________ ports. |
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Definition
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Term
| A manager wants to allow HTTP and HTTPS connections to the company web server. To do this, inbound ports _____ and _____ should be open. |
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Definition
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Term
| As the administrator for a company, you need to find out the Internet connections a particular computer has made in the recent past. You also need to see numeric information so that you know the IP address and port numbers of the destination computers. You should execute the __________ command in the Command Prompt window. |
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Definition
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Term
netstat (the original command, shows basic connections)
netstat –a (shows in‐depth TCP and UDP connections)
netstat –an (shows TCP and UDP connections numerically) |
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Definition
| arp -a (displays MAC addresses of other hosts that your computer has recently connected to) |
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Term
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Definition
Port 21
File Transfer Protocol |
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Term
| What port does telnet use? |
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Definition
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Term
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Definition
Port 25
Simple Mail Transfer Protocol |
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Term
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Definition
Port 53
Domain Name System |
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Term
| What ports do HTTP and HTTPS use? |
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Definition
HTTP uses Port 80
HTTPS uses Port 443
Hypertext Transfer Protocol |
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Term
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Definition
Port 110
Post Office Protocol Version 3 |
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Term
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Definition
Port 1701
Layer 2 Tunneling Protocol |
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Term
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Definition
Port 1723
Point-to-Point Tunneling Protocol |
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Term
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Definition
Port 389
Lightweight Directory Access Protocol |
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Term
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Definition
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