NACK: Not Acknowledge
Not Acknowledge (NACK), also known as Negative Acknowledgment (NAK), is a response sent from a receiving device to a sending device if the data string is incomplete or the checksum is incorrect.

NACS: NetWare Asynchronous Communication Services
NetWare Asynchronous Communication Services (NACS) is a Novell software that supports Novell's AIO and NASI programming interfaces. NACS promotes the sharing of communications resources, such as modems, asynchronous hosts, and X.25 network services.

NADF: North American Directory Forum
North American Directory Forum (NADF) is an organizations that provide public directory services in North America based on the ITU-T X.500 Recommendations.

NADN: Nearest Active Downstream Neighbor
Nearest Active Downstream Neighbor (NADN) is a concept in Token Ring or IEEE 802.5 networks, which refers to the closest downstream network device from any given device that is still active.

Nagle algorithm
The Nagle algorithm was designed to reduce LAN and other network congestion from TCP applications and remains a standard feature of TCP implementations since 1980s. The Nagle algorithm works by aggregating data on the sending side of TCP applications. It accumulates sequences of small messages into larger TCP packets before data reaches the wire, thereby preventing the generation of unnecessarily large numbers of small packets. When the Nagle algorithm works as designed, TCP applications utilize network resources more efficiently.

NAK: Negative Acknowledgment
Negative Acknowledgment (NAK), also known as Not Acknowledge (NACK), is a response sent from a receiving device to a sending device indicating that the information received contains errors.

Name Caching
Name Caching is a method by which remotely discovered host names are stored by a router for use in future packet-forwarding decisions to allow quick access.

Name Resolution
Name Resolution is the process of associating a name with a network location.

Name Server
Name Server is connected to a network that resolves network names (such as URL) into network addresses (such as IP addresses).

Namespace
A namespace is an abstract container providing context for the items (names, or technical terms, or words) it holds and allows disambiguation of items having the same name (residing in different namespaces - compare: URL). As a rule, names in a namespace cannot have more than one meaning, that is, two or more things cannot share the same name. A namespace is also called a context, as the valid meaning of a name can change depending on what namespace applies.

Naming Scheme
A naming scheme is a plan for naming objects. Naming schemes are often used for objects connected into computer networks.

NANOG: North American Network Operator's Group
North American Network Operator's Group (NABOG) is the primary forum for information exchange among U.S. exchange point participants, Internet service providers, and end users.

NAP: Network Access Point
Network Access Point (NAP) is the location for interconnection of Internet service providers in the United States for the exchange of packets.

Napster
Napster, one of the most popular peer-to-peer applications, allowed its members to exchange music files over the Internet for free. Napster implemented a relatively simple IP-based protocol for communicating control operations and data. Napster also implemented a custom name space similar to, but separate from, DNS.

NAPT: Network Address Port Translation
Network Address Port Translation (NAPT) is a method by which many network addresses and their TCP/UDP ports are translated into a single network address and its TCP/UDP ports. Together with the basic NAT (Network Address Translation), it provides a mechanism to connect a realm with private addresses to an external realm with globally unique registered addresses.

Narrowcast
Narrowcast is the transmission of data to a specific list of recipients. The Internet uses both a broadcast and a narrowcast model. Most Web sites are on a broadcast model since anyone with Internet access can view the sites. However, sites that require one to log-in before viewing content are based more on the narrowcast model. Push technologies which send information to subscribers are another form for narrowcasting. Perhaps the best example of narrowcasting are electronic mailing lists where messages are sent only to individuals who subscribe to the list.

NAS: Network Attached Storage
Network Attached Storage (NAS) is a data storage mechanism that uses special devices connected directly to the network media. These devices are assigned an IP address and can then be accessed by clients via a server that acts as a gateway to the data, or in some cases allows the device to be accessed directly by the clients without an intermediary.

NASI: NetWare Access Server Interface
NetWare Access Server Interface (NASI) is a software of Novell which allows clients to connect to asynchronous resources attached to a router. NASI clients are connected to the Ethernet interface 0 on the router. When the user on the NASI client uses the Windows or DOS application to connect to the router, a list of available terminal and virtual terminal lines appears. The user selects the desired outgoing terminal and virtual terminal port.

NASI: NetWare Asynchronous Support Interface
NetWare Asynchronous Support Interface (NASI) is a Novell software which supports NetWare systems with ATM network.

NAT: Network Address Translation
Network Address Translation (NAT) is a method by which IP addresses are mapped from one group to another, transparent to end users. NAT allows an Internet Protocol (IP) network to maintain public IP addresses separately from private IP addresses. NAT is a popular technology for Internet connection sharing. It is also sometimes used in server load balancing applications on corporate networks.

National LambdaRail
National LambdaRail is a high-speed national computer network in the United States that runs over fiber-optic lines, and is the first transcontinental Ethernet network. The name is shared by the organization of research institutions that developed the network, and, to date, plans to continue developing it. LambdaRail is similar to the Abilene Network, but LambdaRail permits deeper experimentation than Abilene does.

NAU: Network Addressable Unit
Network Addressable Unit (NAU), also known as Network Accessible Unit, is an IBM SNA term for an addressable entity. Examples include LUs, PUs, and SSCPs. NAUs generally provide upper-level network services.

NAUN: Nearest Active Upstream Neighbor
Nearest Active Upstream Neighbor (NAUN) is a term in the Token Ring or IEEE 802.5 networks, which is the closest upstream network device from any given device that is still active.

NBDDS: NetBIOS Datagram distribution service
NetBIOS Datagram Distribution Service(NBDDS) is one of the three services provided by NetBIOS. Datagram mode is "connectionless". Since each message is sent independently, they must be smaller; the application becomes responsible for error detection and recovery.

NBNS: NetBIOS Name Service
NetBIOS Name Service (NBNS) is one of the three services provided by NetBIOS. NBNS is for name registration and resolution. In order to start Sessions or distribute Datagrams, an application must register its NetBIOS name using the Name service. NetBIOS names are 16 bytes in length and vary based on the particular implementations.

NBS: National Bureau of Standards
National Bureau of Standards (NBS) is an organization that was part of the U.S. Department of Commerce.

NBSS: NetBIOS Session Service
The NetBIOS Session Service (NBSS) is one of two ways by which applications may communicate with each other, the alternative being the NetBIOS Datagram service. NetBIOS Session Service is for connection-oriented communications. NBSS lets two computers establish a connection for a "conversation", allows larger messages to be handled, and provides error detection and recovery. The bulk of all NetBIOS traffic generated on a network occurs using the NetBIOS Session service, which utilizes TCP port 139. File and printer services are the primary user of the NetBIOS Session service. Another common use for NBSS is the networked application: Server Manager, User Manager, Event Viewer, Registry Editor, and Performance Monitor.

NCIA: Native Client Interface Architecture
Native Client Interface Architecture (NCIA) is an SNA applications-access architecture, developed by Cisco, that combines the full functionality of native SNA interfaces at both the host and the client with the flexibility of leveraging TCP/IP backbones. NCIA encapsulates SNA traffic on a client PC or workstation, providing direct TCP/IP access while preserving the native SNA interface at the end-user level. In many networks, this capability obviates the need for a standalone gateway and can provide flexible TCP/IP access while preserving the native SNA interface to the host.

NCP: Network Control Point
Network Control Point (NCP) may have different meanings depending on the context. 1) In IBM SNA, it refers to a host-generated network control program ( ran on an IBM 3704, 3705 or 3745) that controls the operation of a communications controller. 2) In Virtual Private Network (VPN), it is a centralized database that stores a subscriber's unique VPN definition. Highly sophisticated, this database screens every call and applies call processing control in accordance with customer-defined requirements. 3) Within the AT&T signaling network, NCP is the process that sends routing requests to a Customer Routing Point (CRP).

NCP: Network Control Program
Network Control Program (NCP) is an SNA program that routes and controls the flow of data between a communications controller (in which it resides) and other network resources.

NCSA: National Center for Supercomputing Applications
National Center for Supercomputing Applications (NCSA) is one of five original centers in the National Science Foundation's Supercomputer Centers Program and a unit of the University of Illinois at Urbana-Champaign. Its new headquarters is simply referred to as the NCSA Building. The NCSA Building is directly north of the Siebel Center for Computer Science. The Center's array of supercomputers remain housed at the Advanced Computation Building.

NDIS: Network Driver Interface Specification
The Network Driver Interface Specification (NDIS) is an application programming interface (API) for network interface cards (NICs). It was jointly developed by Microsoft and 3Com Corporation, and is mostly used in Microsoft Windows on Intel-based computers, but the open-source ndiswrapper project allows many NDIS-compliant NICs to be used with Linux. Basically, Network Driver Interface Specification (NDIS) enables a single network interface card (NIC) to support multiple network protocols. For example, with NDIS a single NIC can support both TCP/IP and IPX connections. NDIS can also be used by some ISDN adapters.

NE: Network Element
Network Element (NE), typically a combination hardware and software system, is an equipment designed to perform a networking and telecommunications service function. NEs provide support or services to the user and can be managed through an element management system (EMS). A group of interconnected network elements forms a network. For example, an NE is part of the network equipment where a transport entity (such as a line, a path, or a section) is terminated and monitored.

Neighborhood
Neighborhood in networking refers to a grouping of subscribers, computers, and shared or private cable modems associated with an account administered in the User Registrar Admin UI. A neighborhood contains settings for auto-provisioning modems as shared or private through the User Registrar Subscriber UI.

Neighboring Routers
Neighboring Routers, a concept in the Open Shortest Path First (OSPF) protocol based network, refers to routers that have interfaces to a common network. On multiaccess networks, neighbors are discovered dynamically by the OSPF Hello protocol.

NET: Network Entity Title
Network Entity Title (NET) is a type of network addresses defined by the ISO network architecture. Network Entity Title is used in CLNS-based networks to identify the network layer of a system without associating that system with a specific transport layer entity (as an NSAP address does). NETs are useful for addressing intermediate systems (ISs), such as routers, that do not interface with the transport layer. An IS can have a single NET or multiple NETs, if it participates in multiple areas or domains.

Netburp
Netburp, also known as netsplit, refers to the instance that large numbers of people on the Instant Relay Chatting (IRC) network seem to be signing off at the same time. Netburp may be caused due to a busy and overloaded network when netlag gets really bad, and delays between IRC servers exceed a certain threshhold, the network effectively becomes partitioned for a period of time. People then signing back on again when things get better.

Netflow
Netflow is a Cisco IOS software feature and also the name of an open (but proprietary) Cisco protocol for collecting IP traffic information. Cisco routers with netflow enabled generate netflow records, which are exported from the router in UDP packets and collected using a netflow collector. Juniper Networks provides a similar feature for its routers called cflow.

Netiquette
Netiquette, a combination of two words: Net Etiquette, refers to proper behaviors on a network.

Netmask
Netmask is a 32-bit number indicating the range of IP addresses residing on a single IP network/subnet/supernet.

Netsplit
Netsplit (also known as netburp), a term in Internet Relay Chat, describes the disconnection of a node or a group of nodes from the previously established chatting network or between two nodes.

Netsukuku
Netsukuku is a type of physical mesh network that generates and sustains itself autonomously. There must be computers linked physically to each other, then Netsukuku will build the routes. It is designed to handle an unlimited number of nodes with minimal CPU and memory resources. It can be used to build a worldwide network, separated from the Internet, without the support of any servers, ISPs or authority controls.

NetView
NetView is the IBM network management architecture and related applications. NetView is a VTAM application used for managing mainframes in SNA networks.

Network Access Server
A network access server (NAS), also known as a "media gateway" or a "remote access server" (RAS), is an access control point for remote users connecting to a company's internal network or to an ISP via analog modems or ISDN. A network access server has interfaces to both the local telecommunication service provider such as the phone company and to the Internet backbone. A network access server (NAS) may include its own authentication services or rely on a separate authentication server to verify users. A NAS may be a dedicated server or a software service within a regular server.

Network Adapter
Network Adapter is a hardware device that translates electronic signals between a computing device's native network hardware and the transmission media. A network adapter may also include memory or additional hardware or firmware to aid or perform the computing device's network operations.

Network Address
Network address is the identification of a network component at the network layer (layer 3). It serves as a unique identifier for a computer on a network. Computers can send messages to other computers and components on the network using the network addresses. One of the best known forms of network addressing is the Internet Protocol (IP) address.

Network Administrator
A network administrator is the person in a company responsible for computer network management, including both the hardware and software of the network.

Network Analyzer
Network Analyzer is a hardware or software device that monitors and analyses data traveling over a network. Network Analyzer offers various network troubleshooting features, including protocol-specific packet decodes, specific preprogrammed troubleshooting tests, packet filtering, and packet transmission.

Network Architecture
Network Architecture is the blueprint that provides a framework and technology foundation for designing, building and managing a communication network. Network architecture defines every aspect of a data network's communication system, including but not limited to the types of user interfaces employed, the networking protocols used and the structure and types of network cabling that may be used. A network architecture typically has a layered structure. Layering is a modern network design principle which divides the communication tasks into a number of smaller parts, each part accomplishing a particular sub-task and interacting with the other parts in a small number of well-defined ways.

Network Bottleneck
Network bottleneck refers to the point in computer network at which information is processed more slowly. Network bottleneck may be any network element (a hard drive, I/O card or network interface card NIC) that slows network connectivity rates.

Network Byte Order
Network Byte Order is the order in which the bytes of a multi-byte number are transmitted on a network. This may or may not match the order in which numbers are normally stored in memory for a particular processor.

Network Coding
Network coding is a field of information theory and coding theory and is a method of attaining maximum information flow in a network. The core notion of network coding is to allow mixing of data at intermediate network nodes. A receiver sees these data packets and deduces from them the messages that were originally intended for that data sink.

Network Complexity
Network complexity is the number of nodes and alternative paths that exist within a computer network, as well as the variety of communication media, communications equipment, protocols, and hardware and software platforms found in the network. A simple network is a small LAN with no alternative paths based on a single communication protocol suite while a complex network may be an enterprise-wide network that uses multiple communication media and protocols to interconnect geographically distributed networks with dissimilar hardware and software platforms.

Network Compliance
Network Compliance refers to preparing your network to satisfy government regulations such as HIPAA, SOX and the GLB Act which require changes to many network security infrastructures and IT procedures.

Network Computing
Network computing refers to computers working together over a network. Network computing is a notion raised to challenge the situation where stand-alone workstations & personal computers had come to dominate the computing landscape. In network computing, thin clients were replaceable, but personal information & computing activity was retained on central computers. With the advent of the World Wide Web, any server became a centralized data repository, and any browser could turn a computer into a thin client.

Network Computing System
Network Computing System is a middleware that allows personal computers (clients) to obtain needed information from databases in a central computer (server).

Network Control Program
The Network Control Program was the original protocol suite of the ARPANET. On the ARPANET, the physical layer, the data link layer, and the network layer protocols were all specified by the Host/IMP Protocol in BBN Report 1822.

Network Diagnose
Network Diagnose refers to the process of identify problems in a network. There are many software and hardware tools to assist the network diagnose process.

Network Diagram
Network diagrams, also known as network maps, are commonly used to depict hardware nodes as well as the connections between them. There are many software tools available to draw a network diagram automatically.

Network Driver Interface Specification (NDIS) interface library
Network Driver Interface Specification (NDIS) interface library allows protocol drivers in a PC to send and receive packets on a network. NDIS interface library includes a group of software modeled as a set of abstract functions that either cause a request to be submitted to the operating system or cause a local action to be performed that does not require full communications with other software functions.

Network Gateway
A network gateway is an internetworking system that joins two networks with different protocols together. A network gateway can be implemented completely in software or hardware, or as a combination of the two. Depending on their implementation, network gateways can operate at any level of the OSI model from application protocols to low-level signaling. Because a network gateway by definition appears at the edge of a network, related functionality like firewalling tends to be installed on the network gateway.

Network Health
Network health is a concept used in network management to indicate the robustness of network operation. Parameters such as bandwidth utilization, network downtime or availability etc. are often used to identify network health issues.

Network Interface
Network interface may mean different things in different situations. For example, network interface may be the point of interconnection between a user terminal and a private or public network; the network card on a computer (in casual usage); the point of interconnection between a publicly switched telephone network and a privately owned terminal; the point of interconnection between one network and another network.

Network Layer
Network Layer is the layer 3 of the OSI reference model. This layer provides connectivity and path selection between two end systems. The network layer is the layer at which routing occurs. The mostly often used protocol at the network layer is the Internet Protocol (IP).

Network logon
Network logon refers to logging on to a computer using network credentials remotely from another computer.

Network Management
Network management refers to the maintenance and administration of computing and telecommunication networks. Network Management typically covers five areas: network performance management, network device and application configuration management, network utilization and accounting management, network device and application fault management, and security management. The ISO has established a network management model and the above five conceptual areas are well defined in the model.

Network Map
Network maps, also known as network diagrams, are commonly used to depict hardware nodes as well as the connections between them. There are many software tools available to draw a network diagram/map automatically.

Network Mapping
Network mapping is the study of the physical connectivity of the Internet. It is not to be confused with the remote discovery of which operating system a computer is running, an activity more akin to hacking.

Network mapper
Network mapper is a type of tool for generating information that can be used to map or diagram the arrangement of hosts on a network. Nmap is one of network mapper tool, which is a free and open source utility.

Network monitor
Network monitor is generic name for a type of network monitoring tools that are used to view network devices and service activities, user activities as well as monitoring network traffic at the packet level.

Network monitoring
Network monitoring describes the use of a system that constantly monitors a computer network for slow or failing systems and that notifies the network administrator in case of outages via email, pager or other alarms. While an intrusion detection system monitors a network for threats from the outside, a network monitoring system monitors the network for problems due to overloaded and/or crashed servers, network connections or other devices.

Network Number
Network Number is the part of an IP address that specifies the network to which the host belongs. In classless routing, IP addresses consist of a network number (the combination of the network number and subnet number) and a host number. In classful IP, the network number and host number are derived from the IP address using a bitmask whose value is determined by the first few bits of the IP address. In order to determine the network to which a given route applies, an IP host must know both the network number AND the subnet mask for that network.

Network of Workstations
Network of Workstations (NOW), also known as Cluster of Workstations (COW), is a computer network which connects several computer workstations together, and by utilising special software it allows to use the network as a cluster.

Network Operator
Network Operator is a person who routinely monitors and controls a network, performing such tasks as reviewing and responding to traps, monitoring throughput, configuring new circuits, and resolving problems.

Network Perimeter
A network perimeter is the boundary between the private and locally managed-and-owned side of a network and the public and usually provider-managed side of a network.

Network Port
In computer hardware, a network port serves as an interface between a computer and the network. These hardware ports have different physical shapes such as male, female, round, rectangular, square, oblong, etc. In the context of wavelength routing, a network port is a port that tandems through the node; that is, it is a port on the NE that points to another wavelength router. In the TCP and UDP protocols used in computer networking, a port is a special number present in the header of a data packet that is used to map data to a particular process running on a computer.

Network Redirector
A network redirector, or just redirector, is an operating system driver that sends data to and receives data from a remote device. A network redirector often provides mechanisms to locate, open, read, write, and delete files and submit print jobs.It also makes available application services such as named pipes and mailslots. When an application needs to send or receive data from a remote device, it sends a call to the redirector. The redirector provides the functionality of the Application layer and Presentation layer of the OSI model.

Network Routing Method
Network routing methods, a key element of network architecture, refers to the algorithms that route messages from senders to receivers in a network. The network routing method specifies how, when and to whom data is transferred. Some networks can have more than one routing methods.

Network Security
Network security covers such issues as network communication privacy, information confidentiality and integrity over network, controlled access to restricted network domains and sensitive information, and using the public network, such as Internet, for private communications. To address these issues, various network and information security technologies have been developed by various organizations and technology vendors.

Network Switch
A network switch is a device that joins multiple computers together at a low-level network protocol layer. Technically, network switches operate at layer two (Data Link Layer) of the OSI model. Network switches are capable of inspecting the data packets as they are received, determining the source and destination device of that packet, and forwarding that packet appropriately. By delivering messages only to the connected device that it was intended for, network switches conserve network bandwidth and offer generally better performance than hubs.

Network Tap
A network tap, also known as Test Access Port (TAP), is a hardware device which plugs directly into the network cable and sends a copy of the network traffic to another device. Network taps usually are used for Network Intrusion Detection Systems, network intrusion prevention systems (IPS), network Probes and Analyzers. Duplicating traffic for network devices is typically done now by switch port analyzer (SPAN ports) on network switches, also known as port mirroring.

Network Topology
Network Topology is the specific physical, logical, or virtual, arrangement of the network components and devices (nodes). Network topology is determined only by the configuration of connections between nodes. Distances between nodes, physical interconnections, transmission rates, and/or signal types are not effects in a network topology.

Neural Network
A neural network is an interconnected group of artificial or biological neurons. There are two major groups of neural networks: (1) Biological neural networks, for example the human brain or parts thereof. (2) Artificial neural networks originally referred to as electrical, mechanical or computational simulations or models of biological neural networks.

NFAS: Non-Facility Associated Signaling
Non-Facility Associated Signaling (NFAS) is a classification of signalling protocols that provide the signalling channel in a separate physical line from the bearer channels.

NGN: Next Generation Networking
Next Generation Network (NGN) is a broad term for an integrated network that will offer voice, data, video services over both wireline and wireless infrastructure. The technologies required for the NGN is evolving.

NHS: Next Hop Server
Next Hop Server (NHS), a type of server based on the NBMA Next Hop Resolution Protocol (NHRP), maintains next-hop resolution cache tables containing the IP-to-ATM address mappings of associated nodes and nodes that are reachable through routers served by the NHS.

NIC: Network Interface Card
Network Interface Card (NIC) provides a hardware interface between a computer and a network. The term NIC most commonly refers to network adapter hardware in the form factor of an add-in card. These devices plug into the system bus of the PC and include jacks for network cables. NICs are usually Ethernet adapters, but some NICs support alternate physical layer protocols like ATM. Many of the NICs come pre-installed as part of a total computer system configuration. The primary consideration with Ethernet NICs is the speed they support -- 10 Mbps traditionally, 100 Mbps Fast Ethernet, or both (dual-speed). Some Ethernet NICs include a built-in dial-up modem on the card.

NIPRNET: Non-secure Internet Protocol Router Network
Non-secure Internet Protocol Router Network (NIPRNET), also called as Unclassified but Sensitive Internet Protocol Router Network, is a network of Internet protocol routers owned by the United States Department of Defense (DOD). Created by the Defense Information Systems Agency (DISA), NIPRNET is used to exchange unclassified but sensitive information between "internal" users as well as providing users access to the Internet.

NIS: Network Information System
Network Information System (NIS), also known as Network Information Service, is a protocol developed by Sun Microsystems for the administration of network-wide databases. NIS essentially uses two programs: one for finding a NIS server and one for accessing the NIS databases.

N-ISDN: Narrowband ISDN
Narrowband ISDN (N-ISDN) is the communication standards developed by the ITU-T for baseband networks. N-ISDN is based on 64-kbps B channels and 16- or 64-kbps D channels.

NIST: National Institute of Standards and Technology
National Institute of Standards and Technology (NIST) is a unit of the US Commerce Department. Formerly known as the National Bureau of Standards, NIST promotes and maintains measurement standards. It also has active programs for encouraging and assisting industry and science to develop and use these standards.

NLBS: Network Load Balancing Services
Network Load Balancing Services (NLBS) is a proprietary Microsoft implementation of clustering and load balancing that is intended to provide high availability and high reliability, as well as high scalability. NLBS is intended for applications with relatively small data sets that rarely change (one example would be web pages), and do not have long-running-in-memory states. These types of applications are called stateless applications, and typically include Web, File Transfer Protocol (FTP), and virtual private networking (VPN) servers.

NLESO: Network-level Extended Security Option
Network-level Extended Security Option (NLESO) is one of the two kinds of extended IP Security Option (IPSO) fields defined by the DNSIX 2.1 specification. The other one is the Auxiliary Extended Security Option (AESO) field. Network-level Extended Security Option (NLESO) processing requires that security options be checked against configured allowable information, source, and compartment bit values, and requires that the router be capable of inserting extended security options in the IP header.

NLM: NetWare Loadable Module
NetWare Loadable Module (NLM) is an individual program that can be loaded into memory and can function as part of the NetWare NOS.

NLRI: Network Layer Reachability Information
Network Layer Reachability Information (NLRI) is included in BGP routing update messages which describe a route and how to get there. In this context, an NLRI is a prefix. A BGP-update message carries one or more NLRI prefixes and the attributes of a route for the NLRI prefixes; the route attributes include a BGP next hop gateway address, community values, and other information.

NMS: Network Management System
Network Management System (NMS) is a combination of hardware and software used to monitor and administer a network. An NMS may perform one or more of the following functions: network performance management, network device and application configuration management, network utilization and accounting management, network device and application fault management, and security management.

NMVT: Network Management Vector Transport
Network Management Vector Transport (NMVT) is the SNA message consisting of a series of vectors conveying network management-specific information.

NN: Network Node
Network Node (NN) is the SNA intermediate node that provides connectivity, directory services, route selection, intermediate session routing, data transport, and network management services to LEN nodes and ENs. The NN contains a CP that manages the resources of both the NN itself and those of the ENs and LEN nodes in its domain. NNs provide intermediate routing services by implementing the APPN PU 2.1 extensions.

NNI: Network-to-Network Interface
Network-to-Network Interface (NNI), also known as Network Node Interface, is an internal interface within a network linking two or more elements. Many technologies such as ATM (ATM PNNI), Frame Relay (Frame RElay NNI) require this type of interface for the communication between network devices.

NNM: Network Node Manager
Network Node Manager (NNM) is a Hewlett Packard OpenView component which manages networks. It uses SNMP to talk to network devices, allowing them to be autodiscovered, monitored and controlled. It also allows historical data to be collected and viewed/graphed.

NNS: Network Node Server
Network Node Server (NNS) is the SNA Network Node (NN) that provides resource location and route selection services for ENs, LEN nodes, and LUs that are in its domain.

NOC: Network Operations Center
Network Operations Center (NOC) is a centralized place housing network switching equipment and management systems and possibly storage devices as well. NOC is also a monitoring center equipped with hardware and software tools and managed by dedicated support engineers.

Node
Node, frequently is used interchangeably with device, is an endpoint of a network connection or a junction common to two or more lines in a network. Nodes can be processors, controllers, or workstations. Nodes, which vary in routing and other functional capabilities, can be interconnected by links, and serve as control points in the network. Node sometimes is used generically to refer to any entity that can access a network.

Nodezilla
Nodezilla is a peer-to-peer network software written in C++ and Java, released under the GNU General Public License. Technically, Nodezilla is a secured, distributed and fault-tolerant routing system (aka Grid network). Its main purpose is to serve as a link for distributed services built on top of it (like chat, efficient video multicasting streaming, File Sharing, secured file store ...).

Nonce
Noce is a random or non-repeating value that is included in data exchanged by a protocol, usually for the purpose of guaranteeing liveness and thus detecting and protecting against replay attacks.

Nonextended Network
Nonextended Network is an AppleTalk network that is assigned only one network number and supports only one zone. Nonextended Network supports addressing of up to 253 nodes within only 1 zone. LocalTalk is an example of a nonextended network.

Non-repudiation Service
Non-repudiation Service is a security service that provide protection against false denial of involvement in a communication.

Nonseed Router
In AppleTalk, nonseed router is one of the three router configuration options: seed, nonseed and soft seed. A nonseed router acquires its local zone and local network information from other routers attached to the same network segment. Note that for a nonseed router to acquire its network configuration properly, there must be at least one other router running on that network segment that has the proper configuration information.

Non-stub Area
Non-stub Area refers to the resource-intensive OSPF area that carries a default route, static routes, intra-area routes, interarea routes, and external routes. Non-stub areas are the only OSPF areas that can have virtual links configured across them and are the only areas that can contain an ASBR.

NORDUnet
NORDUnet is an international collaboration between the Nordic national computer networks for research and education. NORDUnet interconnects these networks and connects them to the worldwide network for research and education and to the general-purpose Internet. NORDUnet provides its services by a combination of leased lines and Internet services provided by other international operators.

Northwest Net
NSF-funded regional network serving the Northwestern United States, Alaska, Montana, and North Dakota. Northwest Net connects all major universities in the region as well as many leading industrial concerns.

NOS: Network Operating System
Network Operating System (NOS) is an operating system that includes special functions for connecting computers and devices into a local-area network (LAN) or Inter-networking. NOS implements protocol stacks as well as device drivers for networking hardware. Some popular NOSs for DOS and Windows systems include Novell Netware, Windows NT and 2000, Sun Solaris and IBM OS/2. The Cisco IOS (Internet Operating System) is also a Network Operating System with a focus on the Internetworking capabilities of network devices.

Notification Code
Notification Code is a code that defines the severity assigned to a given condition under a specific set of circumstances.

NR: Network Registrar
Network Registrar (NR) provides Domain Name Server (DNS) and DHCP services. Network Registrar supplies IP addresses and configuration parameters to DOCSIS cable modems and PCs based on network and service policies, and allocates host names for these devices in DNS.

NREN: National Research and Education Network
National Research and Education Network (NREN) is a component of the High Performance Computing and Communications (HPCC) program designed to ensure the US technical leadership in computer communications through research and development efforts in state-of-the-art telecommunications and networking technologies.

NRM: Normal Response Mode
Normal Response Mode (NRM) is an HDLC mode for use on links with one primary station and one or more secondary stations. In this mode, secondary stations can transmit only if they first receive a poll from the primary station.

NRM: Number of RM Cells
Number of RM Cells (NRM), an ABR service parameter in an ATM network, is the maximum number of cells a source may send for each forward RM-cell.

NRZ: Nonreturn to Zero
Nonreturn to Zero(NRZ) is the signal that maintains constant voltage levels with no signal transitions (no return to a zero-voltage level) during a bit interval.

NRZI: Nonreturn to Zero Inverted
Nonreturn to Zero Inverted (NRZI) is the signal that maintains constant voltage levels with no signal transitions (no return to a zero-voltage level) but interpret the presence of data at the beginning of a bit interval as a signal transition and the absence of data as no transition.

NSA: Non-service-affecting
Non-service-affecting(NSA) is a category of conditions that do not interrupt payload traffic.

NSAP: Network Service Access Point
Network Service Access Point(NSAP) is an network addresses as specified by ISO. An NSAP is the point at which OSI network service is made available to a transport layer (Layer 4) entity.

NSAPI: Network Service Access Point Identifier
Network Service Access Point Identifier (NSAPI) is an index to the PDP (Packet Data Protocol) context that is using the services provided by the lower layer (SNDCP (Sub Network Dependent Convergence Protocol)). One PDP may have several PDP contexts and Network Service Access Point Identifiers.

NSF: National Science Foundation
National Science Foundation (NSF) is the U.S. government agency that funds scientific research in the United States. For example, the now-defunct NSFNET was funded by the NSF.

NSFNET: National Science Foundation Network
National Science Foundation Network (NSFNET) is a large network that was funded and controlled by the NSF. NSFNET provided networking services in support of education and research in the United States, from 1986 to 1995. NSFNET is no longer in service.

NTFS: New Technology File System
New Technology File System (NTFS) is an enhanced file system used on Microsoft Windows NT and later versions of the operating system (Windows 2000, Windows XP, Windows Server 2003 and Windows Vista). NTFS replaced Microsoft's previous File Allocation Table (FAT) system, used in MS-DOS and early versions of Windows.

NTIA: National Telecommunications
and Information
Administration
National Telecommunications and Information Administration (NTIA) is a U.S. government agency that takes a leadership role in a variety of information technology issues including security.

NT-1: Network Termination 1
Network Termination 1 (NT-1) is a device based on ISDN that provides the interface between customer premises equipment and central office switching equipment.

NTRI: NCP/Token Ring Interconnection
NCP/Token Ring Interconnection (NTRI) is a function used by ACF/NCP to support Token Ring-attached SNA devices. NTRI also provides translation from Token Ring-attached SNA devices (PUs) to switched (dial-up) devices.

NTSC: National Television Systems Committee
National Television Systems Committee (NTSC) is a United States TV technical standard, named after the organization that created the standard in 1941. NTSC specifies a 6 MHz-wide modulated signal.

Null Modem
Null Modem is a small box or cable used to join computing devices directly, rather than over a network.

NVE: Network-visible Entity
Network-visible Entity (NVE), also known as NVE socket, is the resource that is addressable through a network. Typically, an NVE is a socket client for a service available in a node.

NYSERNet
NYSERNet is a private non-profit corporation created in 1985 to foster science and education in New York State. Its mission is to advance those network technologies and applications that enable collaboration and to promote technology transfer for research and education, expanding these to government, industry, and the broader community. NYSERNet members include New York State's leading universities, colleges, museums, healthcare facilities, primary and secondary schools, and research institutions.

NZ-DSF: Non zero-Dispersion-Shifted Fiber
Non Zero-Dispersion-Shifted Fiber (NZ-DSF) is a dispersion shifted Single Mode (SM) fiber that has the zero dispersion point near the 1550 nm window.