Term
| Open Systems Interconnection (OSI) and Transmission Control Protocol/Internet Protocol (TCP/IP) |
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Definition
| The most common models used to conceptualize a network. These models act as guidelines that break down how networks function into discrete parts called "layers." Getting into networking and passing the CompTIA Network+ certification exam require understanding these in great detail. |
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Term
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Definition
| Discrete parts of network models used to break down the functioning of a network. |
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Term
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Definition
| Simplified representations of the real thing. Must have at least all the functioning parts of the real item. What constitutes a major item and a minor item is open to opinion. |
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Term
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Definition
| The first (bottom) part of the OSI 7-layer model. |
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Term
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Definition
| The second part of the OSI 7-layer model. |
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Term
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Definition
| The third part of the OSI 7-layer model. |
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Term
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Definition
The fourth part of the OSI 7-layer model.
It is the assumbler/disassembler software, usually part of the computer's operating system. It also initializes requests for packets that weren't received in good order. |
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Term
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Definition
| The 5th part of the OSI 7-layer model. Handles all the sessions for a system. |
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Term
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Definition
The sixth part of the OSI 7-layer model.
Handles data conversion into formats that are readable by the system. |
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Term
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Definition
The seventh part of the OSI 7-layer model.
The most visible part of any network is the software that uses it.
A person who knows nothing about the other parts of a network still knows about this later in terms of the programs they use to do things like read mail and surf the Internet.
However, this doesn't refer to the programs themselves. Rather, it refers to the code built into the operating systems that operates with the programs. |
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Term
| Unsielded Twisted Pair (UTP) cable |
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Definition
| Part of the physical channel through which data is moved between systems. Usually contains four pairs of wires that can transmit and receive data. |
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Term
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Definition
| Part of the physical layer in the OSI 7-layer model. It creates connections between systems on the network. |
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Term
| Network Interface Card (NIC) |
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Definition
Serves as the interface between the PC and the network. Part of the Data Link layer on the OSI 7-layer model.
On older systems, it was a separate card that snapped into an expansion slot. |
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Term
| Media Access Control (MAC) address |
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Definition
| A unique, 48-bit value contained in special firmware burned onto the ROM chip of a NIC. |
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Term
| Organizationally Unique Identifier (OUI) |
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Definition
| The first six hexadecimal digits of a MAC address. Numbers issued by IEEE to a manufacturer, these digits tell what company manufactured the NIC. |
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Term
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Definition
| The last six hexadecimal digits on a NIC and the manufacturer's unique serial number for each NIC they manufacture. |
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Term
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Definition
A container for a chunk of data moving across a network. The NIC creates, sends and receives these. Each one holds about 1500 bytes of data.
Contains a header, a packet and an FCS. |
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Term
| What does the hub do with a frame sent by the NIC? |
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Definition
| Creates an exact copy and sends it to every other system on the network. |
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Term
| How is a frame recognized by the receiving computer? |
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Definition
| It is received by every NIC but only the NIC with the matching MAC address will process it. |
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Term
| Frame check sequence (FCS) |
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Definition
| It is about four bytes long. It uses a cyclic redundancy check (CRC) to verify that the data arrived intact. |
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Term
| Frame check sequence (FCS) |
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Definition
| It is about four bytes long. It uses a cyclic redundancy check (CRC) to verify that the data arrived intact. |
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Term
| Cyclic redundancy check (CRC) |
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Definition
| A type of binary math the receiving NIC uses to verify that the data arrived intact. |
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Term
| Frames on networks serve this purpose. |
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Definition
| Restricts the amount of data a NIC can send at once, giving all NICs a chance to send data over the network in a reasonable span of time. |
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Term
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Definition
| The MAC address FF:FF:FF:FF:FF:FF is processed by every NIC on the system. The sending NIC can use this when it doesn't know the target address of the receiving system to ask for the address of each system on the network. |
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Term
| Without knowing the MAC address the host system |
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Definition
| Uses an IP address or hostname to pick a system out of the crowd. The system with the MAC address being sought will read the request in the broadcast packet and respond with its MAC address. |
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Term
| The classical breakdown of the jobs a NIC does |
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Definition
Logical Link Control (LLC)
Media Access Control (MAC) |
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Term
| Logical Link Control (LLC) job |
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Definition
| Talks to the operating system, places data coming from the software into frames and creates the CRC on each frame. It also deals with incoming frames, processing those that are addressed to its NIC and erasing those that are addressed to other machines on the network. |
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Term
| Media Access Control (MAC) job |
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Definition
| Remembers the NICs own address and attaches NIC addresses (sending and receiving addresses) to the frames. |
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Term
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Definition
| When networks get large enough, you can't use them. |
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Term
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Definition
| Method that ignores the hardware and enables the network to be broken into smaller networks called subnets. |
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Term
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Definition
| Exists in every operating system. Creates unique identifiers for each system and creates a set of communications rules for issues like how to handle data broken into multiple packets and how to ensure those packets get from one subnet to another. |
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Term
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Definition
| Several network protocols designed to work together. TCP and IP do so much of the work that the people who created the group of protocols named them after the biggest two. |
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Term
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Definition
| The networking universe. Almost every network in existence uses it. It is the only protocol suite used on the Internet. |
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Term
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Definition
| A unique, dotted decimal notation (sometimes referred to as dotted octet numbering system based on four, 8-bit numbers. Each number ranges from 0 to 255 and they are separated by periods. |
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Term
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Definition
| A system similar to IPv4 but using four, 32-bit numbers separated by dots. |
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Term
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Definition
Configured by the end user.
No two may be the same on a network.
If two machines share the same IP address, neither one will be able to send or receive data. |
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Term
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Definition
| Connects each of the subnets in a larger network. Uses the IP address rather than the MAC address, to forward data. |
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Term
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Definition
| A container encapsulated by a frame. Contains a header and data. |
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Term
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Definition
| The last one that deals directly with hardware. Everything above this one works strictly within software. |
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Term
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Definition
| chops the requested data into chunks that will fit into a packet (and eventually into the NIC's frame), organize the packets for the benefit of the receiving system, and hand them to the NIC for sending. |
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Term
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Definition
| Must be able to recognize a series of incoming packets as one data transmission, reassemble the packets correctly based on information included in the packets by the sending system, and verify that all the packets for that piece of data arrived in good shape. |
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Term
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Definition
| Any one system may be talking to many other systems at a given moment. |
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Term
| One of the most powerful aspects of a network is that it |
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Definition
| Works with almost any operating system. |
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Term
| Portable Document Format (PDF) |
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Definition
Standard released to ISO in 2007.
Became the ISO 32000 open standard. |
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Term
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Definition
| Remains the premier application for reading PDF documents. |
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Term
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Definition
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Term
| Application Programming Interface (API) |
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Definition
Part of the Application Layer, the top of the OSI 7-layer model.
The code built into all operating systems that enables network aware applications, interfaces that programmers can use to make their programs network aware.
Provides a standard way for programmers to enhance or extend an application's capabilities. |
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Term
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Definition
Consists of four layers.
Application
Transport
Internet
Link/Network Interface |
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Term
| The TCP/IP model doesn't have |
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Definition
| A standards body to define the layers, resulting in a surprising number of variations. |
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Term
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Definition
| Lumps OSI's Layer 1 and Layer 2 into the Link Layer (or Network Interface Layer). It's not that the first two layers are unimportant to TCP/IP but the TCP/IP layer really begins at Layer 3 of the OSI model. |
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Term
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Definition
| Should really be called the "IP Packet" layer. Any device or protocol that deals with pure IP packets (getting an IP packet to its destination) sits on this layer. IP addressing itself is also part of this layer, as are routers and the magic they perform to get IP packets to the next router. IP packets are created at this layer. |
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Term
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Definition
The bottom layer of the TCP/IP model.
Lumps the Physical and Data Link layers into one because TCP/IP really begins at the third layer of the OSI model. |
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Term
| The TCP/IP Transport layer |
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Definition
| Combines features of the OSI Transport and Session layers with a bit of Application layer thrown in. |
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Term
| The TCP/IP layer's main function is |
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Definition
| Assembly and disassembly of data but it also defines other functions such as connection-oriented and connectionless communication. |
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Term
| Post Office Protocol (POP) |
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Definition
Used for sending email messages.
Connection-oriented, requiring that the client and server verify they have a good connection before a message is sent. |
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Term
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Definition
| A connectionless protocol that makes the call without verifying first whether another device is there. |
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Term
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Definition
| Comes from Application layer applications. The transport layer breaks it into chunks, adding port numbers and sequence numbers, creating the TCP segment. The Transport layer then hands the TCP segment to the Internet layer that, in turn, creates the IP packet. |
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Term
| The TCP/IP Application layer |
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Definition
| Combines features of the top three layers of the OSI model. Every application, especially connection oriented applications, must know how to initiate, control and disconnect from a remote system. |
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Term
| Initiate, control and disconnect from a remote system |
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Definition
| Something every application, especially connection-oriented applications, needs to be able to do. Each TCP/IP application uses its own method to do this. |
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Term
| With the exception of the Presentation layer, the TCP/IP model |
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Definition
| Contains everything in the OSI model. |
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Term
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Definition
| Primary diagnostic tools for troubleshooting networks and communication tools for talking to your fellow techs. |
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Term
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Definition
| Ways of connecting computers together. Computers employ many of these. |
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Term
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Definition
| Historical topologies for connecting computers together. |
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Term
| Hybrid, mesh, point-to-point and point-to-multipoint |
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Definition
| Modern topologies for connecting computers together. |
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Term
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Definition
| Uses a single cable that connects all of the computers in a line. A network using this needs termination at each end of the cable to prevent a signal sent from one computer from reflecting at the ends of the cable, quickly bringing the network down. |
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Term
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Definition
| Connects all the computers on a network with a ring of cable. Requires no termination. |
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Term
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Definition
| Work well but suffer from the same problem. The entire network stops working if the cable breaks at any point. |
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Term
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Definition
| Uses a central connection box for all the computers on the network. Offers fault tolerance; if one of the cables breaks, all the other computers can still communicate. |
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Term
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Definition
| Ring topology took shrank the entire ring into a small box. Bus topology did the same. They looked like a star topology until you examined the schematic. |
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Term
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Definition
| How the arrangements of the cables look. |
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Term
| Signaling or logical topology |
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Definition
| How the signal travels electronically. |
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Term
| Mesh topology and point-to-multipoint topology |
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Definition
| Almost all wireless networks use one of them. Rarely used in wired networks. |
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Term
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Definition
| Every computer connects to ever other computer via two or more routes. |
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Term
| Partially meshed topology |
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Definition
| At least two machines have redundant connections. Every machine doesn't have to connect with every other machine. |
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Term
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Definition
| Every computer connects directly to every other computer. |
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Term
| Point-to-multipoint topology |
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Definition
| A single system acts as a common source through which all members of the network converse. |
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Term
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Definition
| Two computers connect directly together with no need for a central device of any kind. You can find it utilized in both wired and wireless networks. |
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Term
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Definition
| A practical application of a topology and other critical technologies that provide methods to get data from one computer to another on a network. |
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Term
| Coaxial (coax), twisted pair and fiber-optic |
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Definition
| All cables can be categorized into these distinct groups. |
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Term
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Definition
Contains a central conductor wire surrounded by insulating material which is, in turn, surrounded by a braided metal shield. Shields data transmissions from electromagnetic interference (EMI).
Used in early bus topology networks to connect computers together. Today, mostly used to enable a cable modem to connect to an Internet Service Provider (ISP). |
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Term
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Definition
| Bayonet-style, stick and twist connectors. |
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Term
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Definition
| Connectors that literally pierce the cable. |
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Term
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Definition
| Relative measure of the resistance (more precisely, the impedance) on a cable. It is the only important measure in coax cabling. |
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Term
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Definition
| The most common type of cabling used in networks. Multiple pairs of wires are twisted around each other at specific intervals and bundled together in a common jacket. The twists reduce interference, called crosstalk. The more twists, the less crosstalk. |
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Term
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Definition
| Consists of twisted pairs of wires surrounded by shielding to protect them from EMI. |
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Term
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Definition
| The most common type of network cabling used today. Consists of twisted pairs of wires surrounded by a plastic jacket. The jacket does not protect from EMI. |
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Term
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Definition
Max Frequency 16 MHz
Max Bandwidth 16 Mbps
Recognized by the TIA/EIA |
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Term
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Definition
Max Frequency 100 MHz
Max Bandwidth 100 Mbps
No longer recognized by the TIA/EIA |
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Term
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Definition
Max Frequency 100 MHz
Max Bandwidth 1000 Mbps
Recognized by the TIA/EIA |
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Term
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Definition
Max Frequency 250 MHz
Max Bandwidth 10000 Mbps
Recognized by the TIA/EIA |
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Term
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Definition
| Higher categories have more twists per foot. More twists equals more reduction in interference. |
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Term
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Definition
The most common size is 6.25/125um.
Almost all network technologies require them in pairs, where one is used for sending and the other is used for receiving. |
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Term
| Duplex fiber-optic cabling |
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Definition
| In response to demand for two-pair cabling, manufacturers often connect two together like a lamp cord to create this popular cabling. |
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Term
| Light-emitting diodes (LEDs) |
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Definition
| Most network technologies that use fiber-optics use these to send signals. |
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Term
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Definition
| A fiber-optic cable that uses LEDs to send light signals. |
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Term
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Definition
| Cables that use lasers to send data. |
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Term
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Definition
The types of fiber cables you need to know for the CompTIA Netowrk+ exam.
However, there are over one hundred different connector types for fiber-optic cables. |
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Term
| Stick and twist, stick and click and paired together. |
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Definition
| Mnemonic for remembering ST, SC and LC connectors for fiber-optic cabling. |
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Term
| Stick and twist, stick and click and paired together. |
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Definition
| Mnemonic for remembering ST, SC and LC connectors for fiber-optic cabling. |
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Term
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Definition
| Predates both networking and the personal computer. |
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Term
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Definition
The recommended standard (RS) upon which all serial communication takes place on the PC.
Dates from 1969 and hasn't been substantially changed in about 40 years. |
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Term
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Definition
A poor option for networking.
Data speed of about 56 Kbps and only point-to-point connections. |
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Term
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Definition
Ancient connections that can run around 2 Mbps. When they are used in networking, the run much slower.
Limited to point-to-point technology.
Uses a 25-pin female connector. |
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Term
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Definition
| Based on the IEEE 1394 standard, it's the only viable alternative cabling option to fiber-optic or UTP. |
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Term
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Definition
| The most common fire ratings for cabling. |
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Term
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Definition
| This rating has no significant fire protection. If you burn it, it creates a lot of smoke and noxious fumes. |
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Term
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Definition
| The proper rating for cabling used in the space between the acoustical tile ceiling and the actual concrete ceiling above, which uses the same name. |
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Term
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Definition
| Provides less fire protection than the highest rated cable, so most installations today do not favor it for runs between floors. |
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Term
| Institute of Electrical and Electronics Engineers (IEEE) |
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Definition
Defines industry-wide standards that promote the use and implementation of technology.
Concentrates on cables and, recognizing that no single type of cable can work in all situations, provides a variety of standards. |
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Term
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Definition
| Took over the job of defining network standards from the private sector in February 1980. |
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Term
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Definition
Defines frames, speeds, distances and types of cabling to use in a network environment.
Sets the standards for networking. The original plan was to set a universal standard for networking but it quickly became apparent that no single solution would fit all needs. |
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