Definitions Flashcards
DHCP
The Dynamic Host Configuration Protocol is a network management protocol used on Internet Protocol networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a client–server architecture.
67 68
DNS
Domain Name System (DNS) An Application-layer protocol that resolves computer and domain names to their IP addresses; it uses UDP port 53.
WAP
access point (AP) A wireless device that serves as the central connection point of a wireless LAN and mediates communication between wireless computers.
ad hoc mode
ad hoc mode Sometimes called “peer-to-peer mode,” it’s a wireless mode of operation typically used only in small or temporary installations. There’s no central device, and data travels from one device to another to reach the destination device.
Address Resolution Protocol (ARP)
An Internetwork-layer protocol used to resolve a host’s IP address to its MAC address. ARP uses a broadcast frame containing the target host’s IP address, and the host that’s assigned the address responds with its MAC address.
Authentication
The process of identifying who has access to the network. The most common form of authentication is a logon with a username and password.
Authorization
The process of granting or denying an authenticated user’s access to network resources.
Baseband
A type of signaling used in networks in which each bit of data is represented by a pulse of electricity (on copper media) or light (on fiber-optic media). These signals are sent at a single fixed frequency, using the medium’s entire bandwidth. LAN technologies use baseband signaling.
Basic input/output system (BIOS)
The firmware found on many PCs that is executed when the computer is powered on. Its primary task is to tell the CPU to perform certain tasks when power is
first applied to the computer, including initializing motherboard hardware, performing a power-on self-test (POST), and beginning the boot procedure.
Broadband
A type of signaling that uses analog techniques to encode binary 1s and 0s across a continuous range of values. Broadband signals move across the medium in the form of continuous electromagnetic or optical waves rather than discrete pulses. Signals flow at a particular frequency, and each frequency represents a channel of data, allowing multiple streams of data on a single wire. TV and cable Internet use broadband signaling.
Broadcast domain
The scope of devices to which broadcast frames are forwarded. Router interfaces delimit broadcast domains because they don’t forward broadcasts, whereas switches and hubs do.
Bus
A collection of wires that carry data from one place to another on a computer’s motherboard.
Byte
A collection of 8 bits that might represent a number or a printable character.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
A media access method in which a device must first listen (carrier sense) to the medium to be sure no other device is transmitting. If two devices transmit at the same time (multiple access), a collision occurs and is detected (collision detection). In this case, all devices involved in the collision wait for a random period of time before transmitting again.
Clear to send (CTS)
A signal an AP generates in response to a request-to-send signal. A CTS signal indicates that the computer that sent an RTS can transmit data. See also access point (AP) and request to send (RTS).
Client
The term used to describe an OS designed mainly to access network resources, a computer’s primary role in a network (running user applications and accessing network resources), and software that requests network resources from servers.
Client-to-site VPN
mode A VPN mode that establishes a VPN connection between a single client computer and a VPN device.
Cloud computing
A networking model in which data, applications, and processing power are managed by servers on the Internet, and users of these resources pay for what they use rather than the equipment and software needed to provide resources.
Cloud storage
A data storage method in which some or all of an organization’s data is stored on servers located offsite and maintained by a storage hosting company.
Collision
The result of two or more devices on the same medium transmitting simultaneously when CSMA/CD is the media access method in use. See also Carrier Sense Multiple Access with Collision Detection (CSMA/CD).
Collision domain
The extent to which signals in an Ethernet bus topology network are propagated. All devices connected to a logical bus topology network are in the same collision domain. Switch and router ports delimit collision domains.
Data Link layer
Layer 2 in the OSI model is responsible for managing access to the network medium and delivery of data frames from sender to receiver or from sender to an intermediate device, such as a router. See also Open Systems Interconnection (OSI) reference model.
Dedicated bandwidth
A property of switches in which each port’s bandwidth is dedicated to the devices connected to the port.
Datagram
The unit of information used by UDP in the Transport layer. A datagram is passed up to the Application layer as data and passed down to the Internetwork layer, where it becomes a packet.
Deencapsulation
The process of stripping the header from a PDU as it makes its way up the communication layers before being passed to the next higher layer. See also protocol data unit (PDU).
Default gateway
The address configured in a computer’s IP address settings specifying the address of a router to which the computer can send packets addressed to devices on other networks.
Denial-of-service (DoS) attack
An attempt
to tie up network bandwidth or services so that network resources are rendered useless to legitimate users.
Disk striping with parity
A fault-tolerant disk configuration in which parts of several physical disks are linked in an array, and data and parity information are written to all disks in this array. If one disk fails, data can be reconstructed from the parity information written on the others.
- RAID 5 – Striping + Parity:
- RAID 6 – Striping with double parity
Distributed denial-of-service (DDoS) attacks
Attacks that use many systems to tie up network bandwidth or services so that network resources are rendered useless to legitimate users.
Dynamic disk
A disk configuration in Windows that can be divided into one or more volumes. You can create up to 1000 volumes per dynamic disk (although no more than 32 are recommended). A dynamic disk offers features that a basic disk doesn’t, namely RAID and disk spanning.
Dynamic Host Configuration Protocol (DHCP)
An Application-layer protocol used to configure a host’s IP address settings dynamically; it uses UDP ports 67 and 68.
Encapsulation
The process of adding header and trailer information to chunks of data.
Encryption
A technology that makes data unusable and unreadable to anyone except authorized users of the data.
Extended star topology
An extension of the physical star topology, in which a central switch or hub is the central connecting point for other switches or hubs that have computers and other network devices attached, forming a star of stars.
Fiber-optic cable
A cable type that carries data over thin strands of glass by using optical (light) pulses to represent bits.
File system
The method by which an OS stores, organizes, and manages access to files on a storage device, such as a hard drive.
File Transfer Protocol (FTP)
An Application-layer protocol used to transfer and manage files across a network; FTP uses TCP ports 20 and 21.
Firewall
A hardware device or software program that inspects packets going into or out of a network or computer and then discards or forwards packets based on a set of rules.
Flood
The process whereby a switch forwards a frame out all connected ports.
Flow control
A mechanism network protocols
use to prevent a destination device from becoming overwhelmed by data from a transmitting computer, resulting in dropped packets.
Frame
A packet with source and destination MAC addresses added and an error-checking code added to the back end. Frames are generated and processed by the network interface. See also packet.
Full-duplex mode
A communication mode in which a device can simultaneously transmit and receive data on the same cable connection. Switches can operate in full-duplex mode, but hubs can’t.
Guest OS
The operating system installed on a virtual machine.
Half-duplex mode
A communication mode in which a device can send or receive data but can’t do both simultaneously. Hubs operate only in half-duplex mode; switches can operate in both half-duplex and full-duplex modes.
Header
Information added to the front end of a chunk of data so that the data can be correctly interpreted and processed by network protocols.
Honeypot
A network device, such as a server, that has been installed as a decoy to lure potential attackers.
Hop
Each router a packet must go through to get to the destination network.
hosted virtualization
A process in which the hypervisor implements OS virtualization by being installed in a general-purpose host OS, such as Windows 10 or Linux, and the host OS accesses host hardware on behalf of the guest OS. See also virtualization.
Hotspot
A public Wi-Fi network that can usually be accessed without an encryption or authentication code.
Hub
A network device that performs the same function as a repeater but has several ports to connect a number of devices; sometimes called a multiport repeater. See also repeater.
Hypervisor
The component of virtualization software that creates and monitors the virtual hardware environment, which allows multiple VMs to share physical hardware resources.
infrastructure as a service (IaaS)
A category of cloud computing in which a company can use a provider’s storage or virtual servers as its needs demand; IaaS is also called “hosted infrastructure.”
infrastructure mode
An operational mode for Wi-Fi networks, in which wireless stations connect through a wireless access point before they can begin communicating with other devices.
