Network Theory Flashcards
Definition of a device
Hardware such as computers, tablets, cell phones, servers, printers, fax machines, switches, and routers.
Definition of physical media
Media that connects devices to a network and transmits data between the devices.
Definition of network adapters
Hardware that translates data between the network and a device.
Definition of network operating systems
Software that controls network traffic and access to common network resources.
Definition of nodes
Any device or computer that can connect to a network and generate, process, or transfer data.
Definition of servers
A network computer or process that shares resources with and responds to requests from computers, devices, and other servers on the network.
Definition of a network segment
A subdivision of a network that links a number of devices or serves as a connection between two nodes.
Definition of a backbone
A very high-speed transmission path that carries the majority of network data. It connects either small networks into a larger structure or server nodes to a network where the majority of client devices are attached.
Definition of a client
A computer or process running on a device that initiates a connection to a server.
Definition of a host
Any device that is connected to a network. It can be a client or a server, or even a device such as a printer, router, or switch.
Definition of a port
Port: The endpoint of a logical connection.
Give all the characteristics of a port
Each server program, or service, is associated with a port.
Enables multiple applications to run over one wire or communication path.
Numbered from 0 to 65,535.
Services use established port numbers to create connections with clients.
Definition of a LAN
LAN: (local area network) A self-contained network that spans a small area, such as a single building, floor, or room.
Definition of a WLAN
WLAN: (wireless local area network) A self-contained network of two or more devices connected by using a wireless connection.
Characteristics of a LAN
Direct connections between all nodes and segments.
Cable or short-range wireless technology.
Ethernet is most commonly implemented.
Token ring, token bus, and FDDI were also used.
Characteristics of a LAN administration
Maintaining devices and cabling.
Maintaining network software.
Performing the installation and deployment, upgrades, and troubleshooting for different applications.
Maintaining a broad range of skills and knowledge about network applications and hardware.
Definition of a WAN
WAN: (wide area network) A network that spans a large area, often across multiple geographical locations.
Definition of GAN
GAN: (global area network): A WAN that includes sites and networks from around the world.
Give all the characteristics of WAN
Connect multiple LANs and other networks using long-range transmission media.
Facilitate communication among users and devices in different locations.
Private or public.
Give all the characteristics of WAN administration
Designing and maintaining the connections between remote segments of a network.
Developing and troubleshooting routing structures.
Working with voice and data systems.
Developing scripts to automate complex network administrative tasks.
Working on security issues.
Helping to implement recovery schemes.
Planning, testing, and implementing hardware and software upgrades.
Give a description of a MAN
Metropolitan area network
Covers an area equivalent to a city or a municipality.
Give a description of CAN
Campus area network
Covers an area equivalent to an academic campus or business park.
Typically owned or used exclusively by an entity.
Give a description of PAN
Personal area network
Connects two to three personal devices with cables.
Smartphones, tablets, and so forth
For personal use
Give a description of WPAN
Wireless personal area network
A variation of a PAN that connects wireless devices that are in close proximity.
No wireless access point; infrared or Bluetooth connection technology.
Give a full description of the Internet
The single largest global WAN.
Publicly owned and operated.
Widely used for sending email, transferring files, and executing online commercial transactions.
IP protocol and addresses
Give a full description of the Intranet
Can be a LAN or WAN.
A private network that uses Internet protocols and services to share information with selected individuals.
Contains information that is segregated from the Internet for confidentiality and security reasons.
Give a full description of Extranet
A private network that grants controlled access to users outside of the network. An extension of an organization's intranet. External user (vendors, suppliers, and clients) access to resources on the extranet.
Definition of an enterprise network
A network that includes elements of both LANs and WANs.
Characteristics of an enterprise network
Private networks are owned by individual organizations.
Provide access to devices and resources for users on or off the premises.
Use technologies for fast data access, email exchange, and collaboration.
Scalable.
Strong security.
Mission-critical applications.
Give a description of Layer 7 of the OSI Model
Enables applications on a network node (device) to request network services such as file transfers, email, and database access.
What is layer 7 of the OSI model
Application
What is layer 6 of the OSI model?
Presentation
What is layer 5 of the OSI model?
Session
What is Layer 4 of the OSI model
Transport
What is layer 3 of the OSI model
Network
What is layer 2 of the OSI model
Data Link
What is layer 1 of the OSI model?
Physical
Give a description of Layer 6 of the OSI Model
Translates Application layer data into an intermediate form that both client and server can process.
Give a description of Layer 5 of the OSI Model
Establishes and controls data communication between applications operating on two different devices, regulating when each device can send data and how much it can send.
Give a description of Layer 4 of the OSI Model
Performs the actual establishment, maintenance, and teardown of the connection. Optionally divides long communications into smaller segments, including error recognition and correction, and data receipt acknowledgment.
Give a description of Layer 3 of the OSI Model
Adds logical addressing (network addresses) and chooses the best route.
Give a description of Layer 2 of the OSI Model
Structures the data into a format appropriate for the transmission medium. Adds physical addresses such as media access control (MAC) addresses or frame relay data-link connection identifier (DLCI) numbers. Usually includes simple error checking.
Give a description of Layer 1 of the OSI Model
Transmits bits (binary digits) from one device to another and regulates the transmission stream over a medium (wire, fiber optics, or radio waves).
Definition of TCP/IP model
A four-layer networking model was developed by the United States Department of Defense (DoD).
What is the network device at layer 7
Application proxy servers
What is the network device at layer 6
Application proxy servers
What is the network device at layer 5
Firewalls
What is the network device at layer 4
Firewalls
What is the network device at layer 3
Layer 3 switches,routers, and firewalls
What is the network device at layer 2
Switches, bridges, and access points
What is the network device at layer 1
Hubs, repeaters, patch panels, cables, and network cards
Definition of encapsulation
Encapsulation: The process of adding delivery information to the actual data transmitted on each layer of the OSI or TCP/IP model.
Definition of de-encapsulation
De-encapsulation: The reverse process of removing delivery information at each layer of the OSI or TCP/IP model as data passes to higher layers at the receiving end.
Give all the characteristics of data encapsulation
Encapsulation at the transmitting end.
De-encapsulation at the receiving end.
Each layer adds or removes information.
Headers and trailers
Definition of a data packet
The data packet: A unit of data transferred between devices that communicate over a network.
Definition of a PDU
PDU: (protocol data unit) A term that refers to the data packets, frames, packets, segments, and datagrams that carry information across a network.
Definition of data transmission
The exchange of data among different computers or other electronic devices through a network.
Give all the data that is transmitted in a data transmission
Voice Graphics Animations Audio Text Video
Give all the characteristics of analog signals
Continuous waves of electromagnetic or optical energy.
The intensity of the signal is measured in volts.
Signal oscillates between maximum and minimum values over time and can take any value between those limits.
Size, shape, and other characteristics of the waveform describe the analog signal and the information it carries.
Give all the characteristics of digital signals
Can have only a discrete value (1 or 0, or a specific voltage), which represents the presence or absence of a signal.
The sequence of ones and zeros is the digital data that can be translated into a digital waveform.
The digital waveform can switch between two voltage levels: zero at the ground or a zero voltage state, and one at a positive or negative voltage level.
Only two signal states exist.
Definition of amplitude
Amplitude: The crest or trough of a wave from the midpoint of the waveform to its top or bottom.
Definition of cycle
Cycle: One complete oscillation of an analog signal.
Definition of frequency
Frequency: The number of complete cycles per second in a wave.
Definition of hertz
Hertz: A measure of the number of cycles per second in an analog signal.
Definition of phase
Phase: A point where a wave’s cycle begins, in relation to a fixed point.
Definition of in phase
In phase: When two waves of the same frequency begin at the same time.
Definition of out-of-phase
Out of phase: When two waves either start at an offset from each other or have different frequencies.
Give all the characteristics of unicast
Source address to the destination address
Nodes not involved ignore the transmission.
Predominant transmission mode on LANs and the Internet.
Referred to as point-to-point communication.
Give all the characteristics of broadcast
Source node to all other network nodes.
Network services relying on broadcast transmissions generate a lot of traffic.
Might be used for checking service availability or advertising services.
Give all the characteristics of multicast
Source node to multicast group nodes.
Nodes not in the multicast group ignore the transmission.
Unicast and broadcast used for communication outside the multicast group.
Give all the characteristics of anycast
Source sends data to the nearest node in the anycast group, which passes it to the next nearest node in the group until all nodes in the group have received the data.
Nodes not in the anycast group ignore the transmission.
Give all the characteristics of bit rate
The number of 1s and 0s transmitted per time unit.
Usually measured in bits per second (bps) or megabits per second (Mbps).
Give all the characteristics of baud rate
The number of symbols transmitted per time unit.
The symbol is defined as a fixed number of bits.
Usually measured in symbols per second.
Definition of media access method
Media access method: A network communications mechanism that determines whether or not a particular node can transmit data on a network at a given time.
Definition of contention base access
Contention-based access: A media access method where nodes compete or cooperate among themselves for media access time. Also called competitive media access.
Definition of controlled media access
Controlled media access: A media access method were a central device controls when and for how long each node can transmit. Also called deterministic media access.
Definition of CSMA/CD
(Carrier Sense Multiple Access/Collision Detection) A contention-based media access method where nodes send data when they deem the channel to be idle, but take steps to retransmit when collisions occur.
Characteristics of CSMA/CD
Designed for use in Ethernet LANs. IEEE 802.3 Nodes can transmit whenever they have data to send. Nodes must detect and manage collisions. Busier networks have more collisions, less efficiency. Process for the sending node: Data to transmit. Check network (carrier sense). Transmit data if nobody else is transmitting, starting with the preamble. Detect collision. Continue to send preamble and jam signal Wait for the backoff period. Retransmit data at staggered intervals.
Definition of CSMA/CA
(Carrier Sense Multiple Access/Collision Avoidance) A contention-based media access method where nodes try to avoid data collisions by transmitting when they deem the channel to be idle.
Give all the characteristics of CSMA/CA
Primarily used in IEEE 802.11–based wireless LANs.
Nodes can transmit whenever they have data to send.
Nodes check for other traffic before sending.
Process for the sending node:
Data to transmit.
Check network (polling).
Send RTS signal.
Wait for all nodes to receive the signal.
Transmit data.
Monitor for other RTS signals.
Definition of multiplexing
Multiplexing: A controlled media access method in which a central device combines signals from multiple nodes and transmits the combined signal across a medium
Definition of TDM
TDM: (Time-Division Multiplexing) A multiplexing method in which the communication channel is divided into discrete time slots that are assigned to each node on a network.
Definition of FDM
FDM: (Frequency-Division Multiplexing) A multiplexing method in which data from multiple nodes is sent over multiple frequencies or channels over a network medium.
Definition of MUX
Mux: (multiplexer) A device that manages multiplexing from the sending end.
Definition of Demux
Demux: (demultiplexer) A device that manages multiplexing from the receiving end.
Give a description of simplex
One-way transmission.
No return path.
Uses full bandwidth.
Give a description of half-duplex
Two-way communication.
One direction at a time.
Uses full bandwidth.
Give a description of full-duplex
Two-way communication.
Simultaneously use both directions.
Do not use full bandwidth.
