Term
| EAP-TLS (Extensible Authentication Protocol with Transport Layer Security) |
|
Definition
| A protocol that defines the use of a RADIUS server as well as mutual authentication, requiring certificates on both the server and every client. |
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Term
| EAP-TTLS (Extensible Authentication Protocol with Tunneled Transport Layer Security) |
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Definition
| A protocol similar to EAP-TLS but only uses a single server-side certificate. |
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Term
|
Definition
| Any network activity that moves between systems within the data center. Network devices seen in east-west traffic include internal routers, internal firewalls, and switches. |
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Term
|
Definition
| A hardware device that has been optimized to perform a task in coordination with other edge devices and controllers. |
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Term
|
Definition
| Router that connects one Autonomous System (AS) to another. |
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Term
|
Definition
| The permissions of all groups combined in any network operating system. |
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Term
|
Definition
| A popular way to scale an application by starting up new instances. Cloud providers make it simple to increase the number of instances as demand grows and reduce the number of instances as demand shrinks. |
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Term
| electromagnetic interference (EMI) |
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Definition
| Interference from one device to another, resulting in poor performance in the device’s capabilities. This is similar to having static on your TV while running a hair dryer, or placing two monitors too close together and getting a “shaky” screen. |
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Term
|
Definition
| Messages, usually text, sent from one person to another via computer. E-mail can also be sent automatically to a large number of addresses, known as a mailing list. |
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Term
|
Definition
| Notification sent by e-mail as a result of an event. A typical use is a notification sent from an SNMP manager as a result of an out-of-tolerance condition in an SNMP managed device. |
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Term
|
Definition
| Program that runs on a computer and enables a user to send, receive, and organize e-mail. |
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Term
|
Definition
| Also known as a mail server, a server that accepts incoming e-mail, sorts the e-mail for recipients into mailboxes, and sends e-mail to other servers using SMTP. |
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Term
|
Definition
| An essential component of a data center’s emergency procedures. The emergency alert system informs employees that there is an emergency, enabling them to respond or evacuate. |
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Term
|
Definition
| The policies and procedures a data center implements to enable effective and safe responses to a wide variety of potential emergencies. |
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Term
|
Definition
| Software or hardware that converts the commands to and from the host machine to an entirely different platform; for example, a program that enables you to run Nintendo games on your PC. |
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Term
|
Definition
| The process of putting the packets from one protocol inside the packets of another protocol. An example of this is IP encapsulation in Ethernet, which places IP packets inside Ethernet frames. |
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Term
|
Definition
| A process that attempts to make some data unreadable to anyone but the owner or intended recipient. Generally, the data is scrambled and unscrambled with cryptographic keys. Encryption plays a critical role in securing traffic sent across open networks such as the Internet. |
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Term
|
Definition
| A combination of a port number, Layer 4 protocol, and an IP address that uniquely identifies a connection. |
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Term
|
Definition
| Each pair consists of two linked sockets, one at each end of a TCP/IP session between two hosts. |
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Term
| Enhanced Data rates for GSM Evolution (EDGE) |
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Definition
| Early cellular telephone technology that used a SIM card; obsolete. |
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Term
| Enhanced Interior Gateway Routing Protocol (EIGRP) |
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Definition
| Cisco’s proprietary hybrid protocol that has elements of both distance vector and link state routing. |
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Term
| enhanced quad small form-factor pluggable (QSFP+) |
|
Definition
| Interface and module specification for hot-pluggable network transceivers up to 40 Gbps. |
|
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Term
| enhanced small form-factor pluggable (SFP+) |
|
Definition
| Interface and module specification for hot-pluggable network transceivers up to 10 Gbps. |
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Term
|
Definition
| Device used in telecommunications rooms that keeps track of humidity, temperature, and more. |
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Term
|
Definition
| In TCP/IP communication, an arbitrary port number chosen by a sending computer for the receiving computer to use as the destination port when it responds. IANA suggests operating systems use 49152-65535 as ephemeral ports, but the actual range varies from OS to OS—anything greater than 1024 may be ephemeral on some platforms. |
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Term
|
Definition
| In TCP/IP communication, an arbitrary port number chosen by a sending computer for the receiving computer to use as the destination port when it responds. IANA suggests operating systems use 49152-65535 as ephemeral ports, but the actual range varies from OS to OS—anything greater than 1024 may be ephemeral on some platforms. |
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Term
|
Definition
| A metal structure used in equipment rooms to secure network hardware devices and patch panels. Most racks are 19" wide. Devices designed to fit in such a rack use a height measurement called units, or simply U. |
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Term
|
Definition
| Open and vendor-neutral Layer 2 network protocol standardized under the IEEE 802.3 umbrella, enabling any company to make interoperable Ethernet equipment. Originally created in the 1970s by Xerox and transferred to the IEEE. |
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Term
|
Definition
| An attack that lures people into connecting to a rogue access point by broadcasting the same SSID as the target network’s access points. |
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Term
| Evolved High-Speed Packet Access (HSPA+) |
|
Definition
| The final wireless 3G data standard, transferring theoretical maximum speeds up to 168 Mbps, although real-world implementations rarely passed 10 Mbps. |
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Term
|
Definition
| Viruses that are literally extensions of executables and that are unable to exist by themselves. Once an infected executable file is run, the virus loads into memory, adding copies of itself to other EXEs that are subsequently run. |
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Term
|
Definition
| E-mail server for every major platform; fast and efficient. |
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Term
|
Definition
| Documents and diagrams that identify the best way out of a building in the event of an emergency. It may also define other procedures to follow. |
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Term
| Extended Service Set (ESS) |
|
Definition
| A single wireless access point servicing a given area that has been extended by adding more access points. |
|
|
Term
| Extended Service Set Identifier (ESSID) |
|
Definition
| An SSID applied to an Extended Service Set as a network naming convention. |
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Term
| Extended Unique Identifier, 48-bit (EUI-48) |
|
Definition
| The IEEE term for the 48-bit MAC address assigned to a network interface. The first 24 bits of the EUI-48 are assigned by the IEEE as the organizationally unique identifier (OUI). |
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Term
| Extended Unique Identifier, 64-bit (EUI-64) |
|
Definition
| A process that generates the last 64 bits of the IPv6 address using a calculation based on a device’s 48-bit MAC address. |
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Term
| Extensible Authentication Protocol (EAP) |
|
Definition
| Authentication wrapper that EAP-compliant applications can use to accept one of many types of authentication. While EAP is a general-purpose authentication wrapper, its only substantial use is in wireless networks. |
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Term
|
Definition
| A network’s connections to the wider Internet. Also a major concern when setting up a SOHO network. |
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Term
|
Definition
| The firewall that sits between the perimeter network and the Internet and is responsible for bearing the brunt of the attacks from the Internet. |
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Term
|
Definition
| Any theoretical source of harm to an organization or its IT operations from outside of the organization itself. External threats such as hackers and malware take advantage of vulnerabilities that exist in the network. |
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Term
|
Definition
| Defines the condition of doors and locks in the event of an emergency, indicating that the doors should close and lock. |
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Term
|
Definition
| Defines the condition of doors and locks in the event of an emergency, indicating that the doors should be open and unlocked. |
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Term
|
Definition
| Crosstalk on the opposite end of a cable from the signal’s source. |
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Term
|
Definition
| Nickname for the 100-Mbps Ethernet standards. Originally applied to 100BASE-TX. |
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Term
|
Definition
| The capability of any system to continue functioning after some part of the system has failed. RAID is an example of a hardware device that provides fault tolerance for hard drives. |
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Term
|
Definition
| A screw-on connector used to terminate small-diameter coaxial cable such as RG-6 and RG-59 cables. |
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Term
| Federal Communications Commission (FCC) |
|
Definition
| In the United States, regulates public airwaves and rates PCs and other equipment according to the amount of radiation emitted. |
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Term
|
Definition
| Device that measures the intensity of light pulses within or at the terminal ends of fiber-optic cables. |
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Term
|
Definition
| A high-speed physical medium for transmitting data that uses light rather than electricity to transmit data and is made of high-purity glass fibers sealed within a flexible opaque tube. Much faster than conventional copper wire. |
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Term
|
Definition
| A self-contained, high-speed storage environment with its own storage arrays, cables, protocols, cables, and switches. Fibre Channel is a critical part of storage area networks (SANs). |
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Term
|
Definition
| When the download provider hashes the contents of a file and publishes the resulting message digest. |
|
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Term
|
Definition
| A computer designated to store software, courseware, administrative tools, and other data on a local area network (LAN) or wide area network (WAN). It “serves” this information to other computers via the network when users enter their personal access codes. |
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Term
| File Transfer Protocol (FTP) |
|
Definition
| Classic protocol for file transfer over TCP/IP networks using ports 20 and 21. Has been mostly displaced by protocols such as HTTP(S) and SSH File Transfer Protocol. |
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Term
|
Definition
| Ratings developed by Underwriters Laboratories (UL) and the National Electrical Code (NEC) to define the risk of network cables burning and creating noxious fumes and smoke. |
|
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Term
|
Definition
| System designed to detect and respond quickly to the presence of fire in a server closet or data center. A good fire suppression system should be able to detect fire, cut power to protect sensitive equipment, displace oxygen with fire-suppressing gases, alert relevant staff, and activate sprinklers (potentially—sprinklers will harm equipment). |
|
|
Term
|
Definition
| A network security device or software that restricts incoming and outgoing network traffic based on pre-defined rules. Individual systems can have their own host-based firewalls, while the broader network can be protected by firewalls running on standalone devices or inside other network devices. |
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Term
| First Hop Redundancy Protocol (FHRP) |
|
Definition
| A method of ensuring high data availability by taking multiple routers and grouping them into a virtual router with a single virtual IP address that clients use as a default gateway. Common FHRP protocols are the open standard Virtual Router Redundancy Protocol (VRRP) and Cisco’s proprietary Hot Standby Router Protocol (HSRP) and Gateway Load Balancing Protocol (GLBP). |
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Term
|
Definition
| The person or robot whose job is to react to the notification of a possible computer crime by determining the severity of the situation, collecting information, documenting findings and actions, and providing the information to the proper authorities. |
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Term
|
Definition
| A naming convention that gives each device only one name that must be unique. NetBIOS used a flat name space. TCP/IP’s DNS uses a hierarchical name space. |
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Term
|
Definition
| Early fiber-optic connector that resulted in a small gap between fiber-optic junctions due to the flat grind faces of the fibers. It was replaced by angled physical contact (APC) connectors. |
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Term
|
Definition
| Technology in modern switches that can detect and block excessive traffic. |
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|
Term
|
Definition
| A stream of packets from one specific place to another. |
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Term
|
Definition
| Stores sets of flows for interpretation and analysis. |
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|
Term
|
Definition
| A document that describes the details of gathering, securing, analyzing, transporting, and investigating evidence. |
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Term
|
Definition
| In Windows Server DNS, the database that stores the DNS records (A, AAAA, CNAME, etc.) for a particular domain. Generically referred to as the zone file outside of Windows Server DNS. |
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Term
|
Definition
| Server that acts as middleman between clients and servers, making requests to network servers on behalf of clients. Results are sent to the proxy server, which then passes them to the original client. The network servers are isolated from the clients by the forward proxy server. |
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Term
| FQDN (fully qualified domain name) |
|
Definition
| The complete DNS name of a system, from its hostname to the top-level domain name. Textual nomenclature to a domain-organized resource. It is written left to right, with the hostname on the left, followed by any hierarchical subdomains within the top-level domain on the right. Each level is separated from any preceding or following layer by a dot (.). |
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Term
|
Definition
| A defined series of binary data that is the basic container for a discrete amount of data moving across a network. Generally, the components of a frame can be broken down into the header (MAC addresses and type), the payload (the actual data being transmitted), and the trailer (the frame check sequence [FCS]). Frames are created at Layer 2 of the OSI model. |
|
|
Term
| frame check sequence (FCS) |
|
Definition
| A sequence of bits placed at the very end (trailer) of a frame that is used to check the primary data for errors by implementing a cyclic redundancy check (CRC). |
|
|
Term
|
Definition
| Open source RADIUS server software for UNIX/Linux systems. |
|
|
Term
|
Definition
| Software that is distributed for free with no license fee. |
|
|
Term
|
Definition
| Problem in older wireless networks with manual settings where the WAP transmitted on one channel and a wireless client was set to access on a different channel. |
|
|
Term
| frequency-hopping spread-spectrum (FHSS) |
|
Definition
| A spread-spectrum broadcasting method defined in the 802.11 standard that sends data on one frequency at a time, constantly shifting (or hopping) frequencies. |
|
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Term
|
Definition
| Fouled up beyond all recognition. |
|
|
Term
|
Definition
| Archive created where every file selected is backed up, and the archive bit is turned off for every file backed up. |
|
|
Term
|
Definition
| Any communication system that enables a device to send and receive data simultaneously. |
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|
Term
|
Definition
| A mesh network where every node is directly connected to every other node. |
|
|
Term
| fully qualified domain name (FQDN) |
|
Definition
| The complete DNS name of a system, from its hostname to the top-level domain name. Textual nomenclature to a domain-organized resource. It is written left to right, with the hostname on the left, followed by any hierarchical subdomains within the top-level domain on the right. Each level is separated from any preceding or following layer by a dot (.). |
|
|
Term
|
Definition
| The strengthening and focusing of radio frequency output from a wireless access point (WAP). |
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|
Term
| Gateway Load Balancing Protocol (GLBP) |
|
Definition
| A Cisco-proprietary version of an FHRP that provides increased data availability through redundancy and load balancing. See First Hop Redundancy Protocol (FHRP). |
|
|
Term
|
Definition
| A router that acts as both a small network’s default gateway and its interface to the ISP’s network. Most common in a SOHO context, though the term is falling out of use. |
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|
Term
|
Definition
| Logs that record updates to applications. |
|
|
Term
|
Definition
| The process of using a mobile device’s built-in GPS capabilities and mobile networking capabilities to set geographical constraints on where the mobile device can be used. |
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|
Term
|
Definition
| A query from an SNMP manager sent to the agent of a managed device for the status of a management information base (MIB) object. |
|
|
Term
|
Definition
| The prefix that generally refers to the quantity 1,073,741,824. One gigabyte is 1,073,741,824 bytes. With frequencies, in contrast, giga- often refers to one billion. One gigahertz is 1,000,000,000 hertz. |
|
|
Term
|
Definition
| A Gigabit Ethernet standard using Cat 5e/6 UTP cabling, with a 100-m maximum cable distance. |
|
|
Term
| gigabit interface converter (GBIC) |
|
Definition
| Modular port that supports a standardized, wide variety of gigabit interface modules. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Tiered arrangement of DNS name servers that distribute the work of storing and translating domain names to IP addresses. |
|
|
Term
|
Definition
| The first 48 bits of an IPv6 unicast address, used to get a packet to its destination. |
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|
Term
| Global System for Mobile (GSM) |
|
Definition
| Early cellular telephone networking standard; obsolete. |
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Term
|
Definition
| A public IPv6 address that every system needs in order to get on the Internet. |
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Term
|
Definition
| Type of software that creates visual representations and graphs of data collected by SNMP managers. |
|
|
Term
|
Definition
| One of three modes used with 802.11n wireless networks wherein everything is running at higher speed. |
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Term
|
Definition
| A feature of Windows Active Directory that enables an administrator to apply policy settings to network users en masse. |
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|
Term
|
Definition
| Collections of network users who share similar tasks and need similar permissions; defined to make administration tasks easier. |
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Term
|
Definition
| In terms of virtualization, an operating system running as a virtual machine inside a hypervisor. |
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|
Term
|
Definition
| A network that can contain or allow access to any resource that management deems acceptable to be used by insecure hosts that attach to the guest network. |
|
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Term
|
Definition
| A VoIP standard that handles the initiation, setup, and delivery of VoIP sessions. |
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Term
|
Definition
| In general use, people who break into computer systems. Those with malicious intent are sometimes considered black hat hackers and those who do so with a positive intent and permission from their target (such as vulnerability testing) are regularly referred to as authorized, white hat, or ethical hackers. Of course, there are middle-ground hackers who do so without permission but also without malicious intent: gray hats. |
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Term
|
Definition
| A form of communication where a device can either send or receive data at any given moment rather than do both simultaneously. |
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|
Term
|
Definition
| Applying security hardware, software, and processes to your network to prevent bad things from happening. |
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Term
|
Definition
| Physical network device, typically a “box” that implements and runs software or firmware to perform one or a multitude of tasks. Could be a firewall, a switch, a router, a print server, or one of many other devices. |
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|
Term
|
Definition
| Tools such as cable testers, time-domain reflectometers (TDRs), optical TDRs (OTDRs), certifiers, voltage event recorders, protocol analyzers, cable strippers, multimeters, tone probes/generators, butt sets, and punchdown tools used to configure and troubleshoot a network. |
|
|
Term
|
Definition
| The fixed-length value that a hash function computes from its input. Hashes have many important jobs in computing, but in networking they are primarily used for authentication and ensuring data integrity. |
|
|
Term
|
Definition
| A mathematical algorithm that converts a sequence of binary digits of any length into a fixed-length value. Any given input always results in the same output. |
|
|
Term
|
Definition
| First section of a frame, packet, segment, or datagram; contains key information about the data being transmitted such as destination and source addresses. |
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|
Term
| heating, ventilation, and air conditioning (HVAC) |
|
Definition
| All of the equipment involved in heating and cooling the environments within a facility. These items include boilers, furnaces, air conditioners and ducts, plenums, and air passages. |
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Term
|
Definition
| A base 16 numbering system (i.e., one with 16 symbols). It uses 10 digits (0 through 9) and 6 letters (A through F) to represent the 0s and 1s of binary numbers in a more human-friendly format. Hexadecimal 9 is equal to decimal 9, and hexadecimal A is equal to decimal 10. |
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|
Term
|
Definition
| A naming scheme where the full name of each object includes its position within the hierarchy. An example of a hierarchical name is www.totalseminars.com, which includes not only the hostname but also the domain name. DNS uses a hierarchical name space scheme for fully qualified domain names (FQDNs). |
|
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Term
|
Definition
| A collection of technologies and procedures that work together to keep an application available at all times. |
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Term
|
Definition
| Logs that track the history of how a user or users access network resources, or how network resources are accessed throughout the network. |
|
|
Term
|
Definition
| The process of remotely controlling household devices, such as lights, thermostats, cameras, and washer and dryer. |
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|
Term
|
Definition
| A network containing one or more honeypots created to in order to lure in hackers. |
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|
Term
|
Definition
| A resource that an administrator sets up for the express purpose of attracting a computer hacker, often using fake data and deliberate vulnerabilities as bait. If a hacker takes the bait, the network’s important resources are unharmed and network personnel can analyze the attack to predict and protect against future attacks, making the network more secure. |
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|
Term
|
Definition
| The passage of a packet through a router. |
|
|
Term
|
Definition
| An older metric used by routers that use RIP. The number of routers that a packet must cross to get from a router to a given network. Hop counts were tracked and entered into the routing table within a router so the router could decide which interface was the best one to forward a packet. |
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Term
|
Definition
| Cabling that connects the equipment room to the work areas. |
|
|
Term
|
Definition
| A single device (usually a computer) on a TCP/IP network that has an IP address; any device that can be the source or destination of a data packet. Also, a computer running multiple virtualized operating systems. |
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|
Term
|
Definition
| The portion of an IP address that defines a specific machine in a subnet. |
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|
Term
|
Definition
| Anti-malware software that is installed on individual systems, as opposed to the network at large. |
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|
Term
|
Definition
| A software firewall installed on a “host” that provides firewall services for just that machine, such as Windows Firewall. |
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Term
|
Definition
| Command-line tool that returns the hostname of the computer it is run on. |
|
|
Term
|
Definition
| An individual computer name in the DNS naming convention. |
|
|
Term
|
Definition
| The predecessor to DNS, a static text file that resides on a computer and is used to resolve DNS hostnames to IP addresses. Automatically mapped to a host’s DNS resolver cache in modern systems. The hosts file has no extension. |
|
|
Term
|
Definition
| Type of VPN connection in which a single host establishes a link with a remote, single host. |
|
|
Term
|
Definition
| Type of VPN connection where a host logs into a remote network as if it were any other local resource of that network. |
|
|
Term
|
Definition
| A complete backup facility to continue business operations. It is considered “hot” because it has all resources in place, including computers, network infrastructure, and current backups, so that operations can commence within hours after occupation. |
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|
Term
|
Definition
| A wireless access point that is connected to a cellular data network, typically 4G. The device can route Wi-Fi to and from the Internet. Hotspots can be permanent installations or portable. Many cellular telephones have the capability to become a hotspot. |
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|
Term
| Hot Standby Router Protocol (HSRP) |
|
Definition
| A Cisco-proprietary version of an FHRP that provides increased data availability through redundancy. See First Hop Redundancy Protocol (FHRP). |
|
|
Term
| HTML (HyperText Markup Language) |
|
Definition
| An ASCII-based script-like language for creating hypertext documents like those on the World Wide Web. |
|
|
Term
|
Definition
| An electronic device that sits at the center of a star topology network, providing a common point for the connection of network devices. In a 10BASE-T Ethernet network, the hub contained the electronic equivalent of a properly terminated bus cable. Hubs have been replaced by switches. |
|
|
Term
| human–machine interface (HMI) |
|
Definition
| In a distributed control system (DCS), a computer or set of controls that exists between a controller and a human operator. The human operates the HMI, which in turn interacts with the controller. |
|
|
Term
|
Definition
| A conglomeration of public and private cloud resources, connected to achieve some target result. There is no clear line that defines how much of a hybrid cloud infrastructure is private and how much is public. |
|
|
Term
|
Definition
| A mix or blend of two different topologies. A star-bus topology, for example, is a hybrid of the star and bus topologies. |
|
|
Term
|
Definition
| A document that has been marked up to enable a user to select words or pictures within the document, click them, and connect to further information. The basis of the World Wide Web. |
|
|
Term
| HyperText Markup Language (HTML) |
|
Definition
| An ASCII-based script-like language for creating hypertext documents like those on the World Wide Web. |
|
|
Term
| Hypertext Transfer Protocol (HTTP) |
|
Definition
| Extremely fast protocol used for network file transfers on the World Wide Web. |
|
|
Term
| Hypertext Transfer Protocol over TLS (HTTPS) |
|
Definition
| A secure form of HTTP in which hypertext is encrypted by Transport Layer Security (TLS) before being sent onto the network. It is commonly used for Internet business transactions or any time a secure connection is required. Also referred to as HTTP over SSL, reflecting the precursor technology to TLS called Secure Sockets Layer (SSL). |
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|
Term
|
Definition
| In virtualization, a layer of programming that creates, supports, and manages a virtual machine. Also known as a virtual machine monitor (VMM). |
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