NA
Neighbor Advertisement, an ICMPv6 Neighbor Discovery message used to answer Neighbor Solicitations, announce address or link-layer changes, and support reachability and duplicate-address procedures.
Read definitionAlphabetical glossary
N glossary terms
54 definitions beginning with N.
54 terms
NAC
Network Access Control, a system that evaluates device or user identity and posture before or during network access. NAC platforms often consume DHCP bindings, DNS telemetry, and IPAM context.
Read definitionName error
The original DNS RCODE description for NXDOMAIN, indicating that the queried domain name does not exist according to an authoritative response. It is distinct from an existing name that lacks the requested record type.
Read definitionName server
A DNS server that answers queries from authoritative data, recursive processing, cache, forwarding, or local policy. The term alone does not specify the server's role.
Read definitionName server identifier (NSID)
An EDNS option by which a requester asks the server to return an implementation-defined identifier for the responding instance. It is useful when many servers share an anycast or load-balanced address.
Read definitionNamed
The traditional daemon process name for BIND DNS server. Administrators use configuration files and tools such as rndc to control it.
Read definitionNaming authority
The organization or system with administrative control over a namespace or zone. Authority is established operationally through delegation and control of authoritative data.
Read definitionNAPTR record
A Naming Authority Pointer record applies ordered rewriting rules to discover services or transform identifiers. It is used in ENUM, SIP, and other naming systems, often together with SRV records.
Read definitionNAT
Network Address Translation changes source or destination IP addresses, often also transport ports, as traffic crosses a boundary. NAT conserves IPv4 space but complicates end-to-end identity and address attribution.
Read definitionNAT64
A translation mechanism that lets IPv6 clients communicate with IPv4 servers by mapping between an IPv6 prefix and IPv4 addresses. DNS64 is commonly paired with it to synthesize reachable AAAA answers.
Read definitionNegative answer
An authoritative response indicating that a name does not exist or that the name exists but lacks the requested type. Resolvers can cache negative answers using the SOA information and applicable rules.
Read definitionNegative caching
Caching of authoritative negative answers so repeated nonexistent-name or missing-type queries do not repeatedly reach authoritative servers. The negative TTL is derived from the SOA according to current rules.
Read definitionNeighbor Advertisement
The expanded name of the ICMPv6 NA message. It carries target and link-layer information and can be solicited or unsolicited.
Read definitionNeighbor cache
A per-interface table mapping IPv6 neighbors to link-layer addresses and reachability states. It is the IPv6 counterpart to the IPv4 ARP cache, with richer state tracking.
Read definitionNeighbor Discovery (ND)
The ICMPv6 framework used for router discovery, prefix discovery, address resolution, neighbor reachability, redirects, and Duplicate Address Detection. It replaces ARP and several IPv4 control mechanisms.
Read definitionNeighbor Solicitation
An ICMPv6 message used to resolve a neighbor's link-layer address, verify reachability, or perform Duplicate Address Detection. It is commonly abbreviated NS.
Read definitionNetwork
A prefix-defined IP block used as a routing, subnet, or administrative object. Product terminology may distinguish a usable network from a larger container or aggregate.
Read definitionNetwork address
The first address in a traditional IPv4 subnet, representing the subnet itself rather than an ordinary host. Point-to-point /31 behavior is an important exception.
Read definitionNetwork bits
The leading address bits selected by a prefix length or subnet mask. They identify the network, while remaining bits identify addresses within it.
Read definitionNetwork container
An aggregate IPAM object that holds subnets or child containers and supports hierarchical allocation. In Infoblox, next-available-network functions can allocate children from a container.
Read definitionNetwork discovery
Automated collection of devices, interfaces, addresses, VLANs, routes, and related data from network infrastructure or cloud APIs. Discovery expands visibility but must be reconciled with intended ownership and status.
Read definitionNetwork view
An administrative routing-domain context that allows overlapping address space to be represented separately. In Infoblox, networks and related IPAM objects belong to a network view.
Read definitionNext available IP
A function that selects an address the IPAM system currently considers available within a specified network or set of networks. Safe use depends on accurate leases, reservations, discovery, exclusions, and transaction locking.
Read definitionNext available network
A function that selects an unused child prefix of a requested size from a parent container. It is commonly used by automation to allocate subnets while preserving centralized ownership.
Read definitionNext closer name
In wildcard and DNSSEC processing, the name one label longer than the closest encloser and on the path toward the original query name. It is used to prove that no closer matching name exists.
Read definitionNext hop
The neighboring router or gateway to which a packet is forwarded on its path to a destination. DHCP can distribute default and classless routes that define next hops.
Read definitionNext-server
A DHCP or BOOTP field or configuration identifying the server from which a client should obtain boot resources. It is commonly paired with a boot filename or URL.
Read definitionNibble boundary
A boundary aligned on a four-bit hexadecimal digit. IPv6 reverse DNS is simplest when prefixes are delegated on nibble boundaries because each label in ip6.arpa represents one hexadecimal digit.
Read definitionNIOS
The Infoblox operating system and DDI software platform used by Grid Masters, DNS/DHCP members, and related appliances or virtual instances. Features and terms vary by NIOS version and license.
Read definitionNIOS-X
Infoblox's cloud-native service architecture for delivering selected networking and security capabilities through managed on-premises or cloud-connected service instances. It is distinct from traditional NIOS Grid architecture.
Read definitionNo-refresh interval
The first phase of Microsoft DNS aging during which repeated refreshes do not update a record's timestamp. It reduces replication traffic while still allowing actual record changes.
Read definitionNODATA
An informal but widely used term for an authoritative response where the queried name exists but no record of the requested type exists. The response normally has NOERROR rather than NXDOMAIN.
Read definitionNode
A position in the DNS namespace that can own one or more resource record sets. A node can exist even without A or AAAA records.
Read definitionNon-authoritative answer
A response based on cache, recursion, forwarding, or local processing rather than the responder's authority for the queried zone. The AA bit is not set.
Read definitionNon-recursive query
A query with the RD bit clear. The server returns data it already has from authority or cache, or a referral, without being asked to perform recursion.
Read definitionNon-temporary address
An ordinary stateful IPv6 address carried in an IA_NA, contrasted with the obsolete IA_TA temporary-address mechanism. The address still has preferred and valid lifetimes.
Read definitionNOTIFY
A DNS message that informs secondary servers that a zone may have changed so they can check the SOA serial and refresh promptly instead of waiting for the normal refresh timer.
Read definitionNS record
A Name Server record identifies an authoritative server for a zone or delegated child. Apex authoritative NS records and parent-side delegation NS records are separate RRsets.
Read definitionNS set
The group of NS records associated with a zone apex or delegation. Redundant servers should be independently reachable and consistently configured.
Read definitionNSEC record
A DNSSEC record that links to the next existing name in canonical order and lists record types present at its owner. It proves name or type nonexistence but can permit zone walking.
Read definitionNSEC3 opt-out
A flag allowing NSEC3 chains in delegation-heavy zones to omit some unsigned delegations. It reduces signing cost but changes the security proof around insecure delegations.
Read definitionNSEC3 record
A hashed denial-of-existence record designed to make straightforward zone enumeration more difficult than NSEC. It adds iterations, salt, and opt-out behavior, with operational and computational tradeoffs.
Read definitionNSEC3PARAM record
A zone-apex record publishing the NSEC3 parameters used to generate hashed owner names, such as algorithm, iterations, and salt. Validators primarily rely on parameters in NSEC3 records themselves.
Read definitionNSID
The abbreviation for Name Server Identifier, an EDNS option used to identify the responding server instance behind a shared service address.
Read definitionNSLOOKUP
A long-standing command-line DNS query tool available on many operating systems. It is useful for basic testing, though dig, Resolve-DnsName, or drill often expose more protocol detail.
Read definitionNSSET
A registry or provisioning object representing the authoritative name servers and sometimes their addresses for a domain. The exact object model depends on the registry protocol or platform.
Read definitionNUD
Neighbor Unreachability Detection, the Neighbor Discovery process that tracks whether a neighbor is reachable and probes when necessary. Neighbor-cache entries move through states such as REACHABLE, STALE, DELAY, and PROBE.
Read definitionNull MX
An MX RRset consisting of a single record with preference 0 and target dot, explicitly stating that the domain accepts no email. It is clearer than relying on failed implicit delivery.
Read definitionNull route
A route that discards matching traffic, often used for emergency mitigation or to make sinkhole destinations unreachable. It operates at IP routing rather than DNS policy.
Read definitionNXDOMAIN
The DNS RCODE indicating that the queried domain name does not exist. It applies to the name, not merely the requested record type, and can be cached as a negative answer.
Read definitionNXDOMAIN hijacking
Replacement of a legitimate NXDOMAIN response with a redirect, search page, advertisement, or other synthesized answer. It can break DNSSEC, application assumptions, and diagnostic accuracy.
Read definitionNXDOMAIN redirection
A policy or service behavior that substitutes another answer when a name should return NXDOMAIN. It may be used for captive portals or policy, but it changes standard DNS semantics.
Read definitionNXDOMAIN spike
A sudden rise in nonexistent-name responses. Causes can include typos, missing suffixes, search-list behavior, stale applications, DGAs, random-subdomain attacks, or failed service discovery.
Read definitionNXNAME record
A DNS record type assigned for compact denial of existence. It is intended to support efficient authenticated nonexistence mechanisms defined by its associated specification.
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