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140 Cards in this Set

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  • Back
Encapsulation refers to the adding of both a header and trailer to the data in the Data Link layer of the OSI.
What are the 7 layers of the OSI model?
Application, Presentation, Session, Transport, Network, Data Link, Physical - All People Seem To Need Data Processing
What are the 2 sublayers of the Data Link Layer of the OSI model?
Logical Link Control (LLC) and Media Access Control (MAC), or also call the hardware address.
Block ID
6 character sequence unique to each NIC vendor - the first 6 characters (of 12) of the MAC address
Device ID
The last 6 characters (of 12) of the MAC address, based on model and manufacture date.
What are 2 types of signaling methods used in data transmission?
Analog and Digital - both are generated by electrical current (volts).
What are 4 characteristics of analog signals?
Amplitude (volts), Frequency (Hz), Wavelength (ft. or m.), and Phase (degrees).
What are digital signals composed of?
Positive voltage (1) and zero voltage (0) expressed as bits.
What does "Overhead" in networking refer to?
It describes the non-data that must accompany data for a signal to be properly routed by a network (such as the Data Link Layer heading and trailer.)
What are 3 types of transmission directions?
Simplex, Half-Duplex and Duplex
What does simplex transmission refer to?
Signals that are transmitted in only one direction.
What does Half-Duplex transmission refer to?
Signals that move in two directions, but only one direction at a time.
What does (Full) Duplex transmission refer to?
Signals that move in both directions simultaneously.
What is a channel?
It's a distinct data path between two nodes.
What does multiplex transmission refer to?
Multiple signals that travel simultaneously on one medium through several subchannels.
What's a multiplexer?
A device that sends multiple signals. (Mux)
What's a demultiplexer?
A device that receives multiple signals. (Demux)
What is statistical multiplexing?
The transmitter assigns slots to nodes not by time, but by priority and need.
Name the 3 types of node relationships:
Point-to-Point, Broadcast and Webcast
Point-to-Point Transmission
Consists of one transmitter and one receiver
Broadcast Transmission
Consists of one transmitter and multiple receivers
Broadcast transmission over the web
A measure of how much data is transmitted over a period of time. (Also called Capacity and Bandwidth). Can be measured in kbps, mbps, Gbps and Tbps.
What are 2 meanings of the term "Bandwidth"?
1) Throughput; 2) measure the difference between the highest and lowest frequencies a medium can transmit.
Transmission form in which digital signals are sent one signal, one channel at a time using Direct Current (DC) pulses.
Transmission form in which signals are modulated as RadioFrequency (RF) waves at different frequencies.
Signals travelling on one wire/cable infringe on a signal travelling on an adjacent wire/cable.
What is noise measured in?
Loss of signal strength as it travels away from the source.
Device that increases the strength (voltage) of signals. (Physical Layer of OSI)
Repeating digital signals in their original form without noise. (Repeater - Physical Layer of OSI)
Device that regenerates digital signals (Physical Layer of OSI)
Time delay that takes place when data travels on a network before reaching its destination.
Populated Segment
Part of a network that contains end nodes (Example: but to connecting users).
Unpopulated Segment (or Link Segment)
Part of a network that doesn't contain end nodes (Example: hub to hub).
Common Network Media Characteristics
Throughput, Cost, Size and Scalability, Connectors, and Noise Immunity
Pieces of hardware that connect wire to the network device.
Media Converter
Hardware that enables networks/segments running different media to interconnect and exchange signals.
Device that transmits and receives signals.
Pipeline to contain and protect cabling from EMI.
Resistance that contributes to controlling the signal (ohms)
Thicknet (Thinwire Ethernet) specifications
10Base-5, 10mbps, 500 meters, RG-8, Bus Topology
Thinnet (Thin Ethernet)
10Base-2, 10mbps, 185 meters, RG-58A/U, Bus Topology
RG-6 (Coaxial Cable)
Cable that comes into a house from the carrier (used with broadband cable).
Cable Modem
Device that modulates and demodulates the broadband cable signals using an F-type connector.
Twist Ratio
Number of twists per meter or foot in Twisted-Pair cables. More twists: expensive, less crosstalk, greater attenuation; Fewer Twists: less expensive, more crosstalk, less attenuation.
Fault Tolerance
Capacity for a component to continue functioning despite damage/partial malfunction.
5-4-3 Rule
2 Communicating nodes on a network can't contain more than 5 network segments connected by 4 repeating devices, and no more than 3 segments may be populated. 500 meters between nodes is maximum.
Layer of plastic covering/surrounding the fibers of a fiber-optic cable.
Optical Loss
Degradation of light signal after it travels a certain distance from light source (Fiber-Optics)
Modal Bandwidth
Measure of the highest frequency of signal a multi-mode fiber can support over specific distance (MHz-Km)
Cable Plant
Hardware that makes up the enterprise-wide cabling system.
Structured Cabling
568 Commmercial Building Wiring Standard released by TIA/EIA in 1991 that states how networking media can best be installed, and divides cabling into 6 subsystems.
Name the 6 subsystems of Structured Cabling.
Entrance facilities, backbone wiring, equipment room telecommunications closet, horizontal wiring, work area.
Demarcation Point
The point of division between the service carrier's network and the internal network.
Punch-down block
Panel of data receptors into which horizontal cabling from the workstations is inserted.
Patch panel
Wall-mounted panel of data receptors into which patch cables from the punch-down block are inserted.
Patch cable
Relatively short section (3-25 feet long) of cabling with connectors on both ends.
Straight-through cable
Patch cable that has both ends of the RJ-45 plug terminated identically.
Crossover cable
Patch cable in which the termination locations of the transmit and receive wires on one end of the cable are reversed.
Bend radium
Radius of the maximum arc into which you can loop a cable before you will impair the data transmission.
Area above the ceiling or below the sub-flooring.
Wireless Spectrum
Continuum of electromagnetic waves used for data and voice communications.
Radiation Pattern
Relative strength over a three-dimensional area of all the electromagnetic energy the antenna sends or receives.
Directional Antenna
Issues wireless signals along a single direction (satellite downlink).
Omnidirectional Antenna
Issues and receives equal strength and clarity in all directions (TV and radio stations).
Range (Wireless)
Geographical area that an antenna or wireless system can reach.
This occurs in wireless signaling when waves encounter an obstacle and reflect or bounce back towards the source.
This occurs when a wireless signal splits into secondary waves when it encounters an obstruction (objects with sharp edges like chairs, books, and outdoors by rain, mist and snow).
This occurs when a wireless signal splits into multiple signals.
Change in signal strength as a result of some of the electromagnetic energy being scattered, reflected, or diffracted after being transmitted.
Transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies (opposite of broadband, by which signals are transmitted at wider frequencies and offer a higher throughput).
Spread Spectrum
Use of multiple frequencies to transmit a signal.
Fixed (Wireless Systems)
The locations of the transmitter and receiver do not move. Point-To-Point link. (Access points can be as far apart as 1000 feet).
Mobile (Wireless Systems)
The receiver can be located anywhere within the transmitter's range. (Stations must remain within 300 feet of an access point).
Ad Hoc (WLAN)
Wireless stations or nodes transmit directly to each other via NICs without an intervening connectivity device.
Multiprotocol Networks
Networks running more than one protocol (Example: TCP/IP and IPX/SPX).
TCP/IP is a suite of network protocols that has many subprotocols such as TCP, IP, UDP and ARP.
Protocols that can span more than one LAN or LAN segment (they carry the network layer addressing information that can be interpreted by a router.
Transmission Control Protocol - operates in the Transport layer of OSI and provides reliable data delivery services; connection-oriented subprotocol; ensures reliable data delivery through sequencing and checksums; provides flow control to ensure that a node is not flooded with data.
User Datagram Protocol - operates in the Transport layer of OSI; connectionless service; provides no assurance that packets will be received in the correct sequence; no error checking or sequencing; lack of sophistication makes it more efficient that TCP; useful in situations where a great volume of data must be transferred quickly (live audio or video).
Internet Protocol - operates in the Network layer of OSI; enables TCP/IP to internetwork (traverse more than one LAN segment and more than one type of network through a router).
IP Datagram
A TCP/IP packet that acts as an envelope for data and contains information necessary for routers to transfer data between different LAN segments.
Loopback address
IP address that is reserved for loopback communications - contacting and testing your own machine. This address is
Dotted Decimal Notation
The most common way to express an IP address:
Subnet Mask
A special 32-bit number that, when combined with a device's IP address, informs the rest of the network about the segment or network to which the device is attached. It's assigned either manually or automatically (DHCP).
Static IP Address
Manually assigned IP address that doesn't change.
Dynamic IP address
IP address that is assigned to a device upon request and is changeable.
With DHCP, a device borrows the IP address on a temporary basis for a specified length of time.
If a DHCP server fails and another is installed to replace it, the clients that relied on the first DHCP server will need to release their old leases using the "ipconfig /release" command line fuction. To renew a lease, use "ipconfig /renew".
Automatic Private IP Addressing - Provides a computer with an IP address automatically if the DHCP server is unreachable; uses pre-defined pool of addresses: through and is assigned a default submask of (Class B network); once the DHCP sever becomes available again, APIPA will release its assigned IP address and allow the client to receive the DHCP address; unsuitable for networks that must communicate with other subnets or over a WAN.
The process's port number plus its host machine's IP address. (Example: for Telnet service with a standard port of 23, the IP address would look like
Well Known Ports
Assigned to processes that only the operating system or an Administrator of the system can access. Range: 0 to 1023.
Registered Ports
Ports that are available to network users and processes that do not have special administrative privileges. Range: 1024 to 49151.
Dynamic and/or Private Ports
Open ports for use without restriction. Range: 49152 to 65535.
Unicast Address
Address that represents a single interface on a device.
Multicast Address
Represents multiple interfaces (often on multiple devices) - useful for transmitting the same data to many different devices simultaneously.
Anycast Address
Represents any one interface from a group of interfaces (often on multiple nodes), any one of which can accept a tranmission.
Format Prefix
Variable-length field at the beginning of the address that indicates what type of address it is.
One of the three components of DNS: Resolvers are any hosts on the Internet that need to look up domain name information.
Name Servers
One of the three components of DNS: Name Servers are servers that contain databases of associated names and IP addresses and provide this information to resolvers on request.
Name Space
One of the three components of DNS: Name Spaces refer to the database of IP addresses and their associated names - address resource records map the IP address to its domain name (Example: IN A
Zero Configuration - collection of protocols designed by IETF to simplify the setup of nodes on a TCP/IP network. It assigns IP addresses, resolves node's host name/IP address without DNS server; enables 2 workstations directly connected to communicate without static IP addressing, DHCP servers or DNS servers. IP addresses are assigned through IPv4LL )IP Version 4 Link Local) - range between and
Terminal emulation protocol used to log on to remote hosts using the TCP/IP protocol suite.
Process of assigning one network component to work with another.
NIC (Network Interface Card) Typical Memory Range
A0000 - FFFFF (some manufacturers prefer certain ranges).
NIC (Network Interface Card) Base I/O Port
Varies depending on manufacturer, but popular addresses are in the 300 range (300 - 30F), 310, 280 and 2F8.
Loopback Plug (Adapter)
Connector that plugs into a port (serial/parallel/RF-45) and crosses ovver the transmit line to the receive line so that outgoing signals can be redirected into the computer for testing/troubleshooting.
Operate in the Physical Layer of OSI; cannot improve or correct bad or erroneous signal; not "intelligent" devices; cannot direct data to destination; suited to bus topology; allows you to extend a network inexpensively.
Repeater with more than one output port; operates in Physical layer of OSI; can contain uplink port, which allows the hub to connect to another hub or connectivity device; serve as central connection point for branches of a star or star-based hybrid topology; share same collision domain.
Multi-Station Access Unit - name of a hub on a Token Ring network.
Collision Domain
Logically or physically distinct Ethernet network segment on which all participating devices must detect and accomodate data collisions.
Passive Hub
Simplest of hubs. Do nothing but repeat signals.
Intelligent (Managed) Hubs
Posses internal processing capabilities like remote management, data filtering, diagnostic information - can be managed from anywhere on the network.
Standalone (Workgroup) Hubs
Hubs that serve a group of computers that are isolated from the rest of the network or that form their own network - can be passive or intelligent.
Single Point Of Failure
Device or connection on a network that, were it to fail, could cause the entire network or portion to stop functioning. Sizable networks rely on multiple connectivity devices to avoid catastrophe.
Stackable Hubs
Resemble standalone hubs, but are designed to be linked with other hubs in a single telecommunications closet - represent one large hub to the network - avoids the problems with single point of failure.
Devices that connect two network segments by analyzing incoming frames and making decisions about where to direct them based on each frame's MAC address (Data Link Layer of OSI). Bridges are protocol independent; can also connect two segments using different Data Link and Physical layer protocols. Bridges move data faster than routers; can also extend a network without extending collision domain.
Filtering Database (Forwarding Table)
Database of known MAC addresses and their locations on the network. Bridges use this to determine whether a packet should be forwarded or filtered.
Connectivity devices that subdivide a network into smaller logical pieces or segments. Operate at Data Link layer of OSI; interpret MAC address information. Switches are like multi-port bridges - have internal processor, operating system, memory and several nodes. Switches turn a shared channel into several channels, each channel it's own collision domain. Pros: better security and performance. Cons: cannot prevent data loss.
Cut-Through Mode
Mode of a switch that reads a frame's header and decides where to forward the data before it reads the entire packet. Cut-through switches can detect runts, but not corrupt packet. Advantage of this mode is speed. Best suited for small workgroups.
Store and Forward Mode
Mode of switch that reads the entire data frame into memory and checks accuracy before transmitting. Suitable for larger LAN environments - don't propagate errors. This type of switch can also transfer data between segments running different transmission speeds - good in mixed environments.
Broadcast Domain
Combination of ports that make up a Layer 2 segment - also known as a subnet. (VLAN and switch).
High-Layer Switch
Also known as routing switches or application switches, they're capable of interpreting data at higher levels of the OSI (Layer 3 & 4). The ability to interpret higher-layer data enables switches to perform advances filtering, statistics keeping and security function. Typically used as part of a network's backbone.
Multiport connectivity device that directs data between nodes on a network. They can integrate LANs and WANs running at different transmission speeds and a variety of protocols. (Layer 3 of the OSI).
Modular Router
A router with multiple slots that can hold different interface cards or other devices (multiple network interfaces and protocols).
Interior Router
A Router that directs data between nodes on an autonomous LAN (workstation to workstation) - they don't direct data between a workstation and a web server on the Internet.
Exterior Router
A router that directs data between nodes external to a given autonomous LAN - operate on the Internet backbone.
Static Routing
Technique in which a network administrator programs a router to use specific paths between nodes - it doesn't account for network congestion, failed connections, or device moves - not optimal.
Dynamic Routing
Automatically calculates the best path between 2 nodes and accumulates this information in a routing table - can detect problems and reroute data through a different path.
Best Path
Refers to the most efficient route from one node on a network to another - depends on the number of hops between nodes, the current network activity, unavailable links, transmission speed and topology.
Convergence Time
Time it takes for a router to recognize a best path in event of a change or network outage.
Brouter (Bridge Router)
Routers that take on some characteristics of bridges. Nonroutable protocols can be forwarded (such as NetBEUI), and can connect multiple network types through one device. (Layer 2 and 3 of OSI).
Combiations of networking hardware and software that connect 2 dissimilar kinds of networks. They may connect 2 systems that use different formatting, communications protocols or architecture. Operate at multiple layers of OSI. Gateways can reside on servers, microcomputer connectivity devices or mainframes.
Email Gateway
Gateway that translates messages from one type of email system to another.
IBM Host Gateway
Gateway that establishes and manages communications between a PC and an IBM mainframe computer.
Internet Gateway
Gateway that allows and manages access between LANs and the Internet.
LAN Gateway
Gateway that allows segments of a LAN running different protocols or different network models to communicate.
Voice/Data Gateway
Gateway that connects part of a network that handles data traffic with the part that handles voice traffic.
Gateway that selectively blocks or filters traffic between networks.