IA
Identity Association, a DHCPv6 structure that groups one or more addresses or prefixes assigned to a client interface or purpose. Each IA is identified by an IAID and has associated timers and lifetimes.
Read definitionAlphabetical glossary
I glossary terms
54 definitions beginning with I.
54 terms
IA Address option
The DHCPv6 option that carries an IPv6 address and its preferred and valid lifetimes within an identity association. It can also contain status or other address-specific suboptions.
Read definitionIA_NA
Identity Association for Non-temporary Addresses. It is the standard DHCPv6 container used to request and assign ordinary stateful IPv6 addresses.
Read definitionIA_PD
Identity Association for Prefix Delegation. It carries one or more delegated prefixes and related T1, T2, preferred, and valid lifetime information.
Read definitionIA_TA
Identity Association for Temporary Addresses, an older DHCPv6 mechanism intended for temporary address assignment. RFC 9915 marks it obsolete.
Read definitionIAID
Identity Association Identifier, a client-chosen value that distinguishes identity associations belonging to the same DUID. It is meaningful together with the client DUID and IA type.
Read definitionIANA
The Internet Assigned Numbers Authority coordinates global registries for protocol parameters, DNS root-zone administration, and allocation of top-level Internet number resources. Its registries are the authoritative source for DNS types, DHCP options, ports, and many other code points.
Read definitionIAPREFIX
The DHCPv6 option nested inside IA_PD that identifies a delegated IPv6 prefix and its preferred and valid lifetimes. It can also carry prefix-related status information.
Read definitionICANN
The Internet Corporation for Assigned Names and Numbers coordinates unique Internet identifiers and performs the IANA functions through its affiliate PTI. It also oversees agreements and policy processes for much of the domain-name ecosystem.
Read definitionICMP
Internet Control Message Protocol, used for error reporting and network diagnostics. ICMPv6 also carries essential IPv6 functions including Neighbor Discovery and Router Advertisements.
Read definitionICMP echo
The request and reply messages commonly used by ping. Some DHCP servers use ICMP echo as one signal in IPv4 conflict detection, though lack of reply does not prove an address is unused.
Read definitionICMPv6
The IPv6 control protocol used for errors, diagnostics, Neighbor Discovery, Router Advertisements, multicast listener functions, and other essential operations. Blocking it broadly can break IPv6.
Read definitionIDN
Internationalized Domain Name, a domain name that represents Unicode characters using an ASCII-compatible encoding in DNS. User interfaces may display native characters while the wire form uses A-labels beginning with xn--.
Read definitionIDNA
Internationalized Domain Names in Applications, the standards framework that maps, validates, and converts Unicode labels for use with the ASCII DNS protocol. Application behavior and registry policy both affect which names are valid.
Read definitionIETF
The Internet Engineering Task Force develops and publishes open Internet protocol standards and operational guidance, primarily as RFCs. DNS, DHCP, and many IPAM-related behaviors are defined through IETF work.
Read definitionIID
Interface Identifier, the lower-order portion of an IPv6 unicast address used to identify an interface within a subnet prefix. Modern IID generation may use stable-random or temporary privacy methods rather than embedding a MAC address.
Read definitionImplied apex NS
An informal description of the authoritative NS RRset located at a zone apex. The parent delegation NS and child apex NS should be operationally consistent, though they are separate RRsets.
Read definitionIN class
The Internet DNS class, numeric value 1, used by nearly all ordinary DNS resource records and queries. Other classes exist but are rarely used for production Internet naming.
Read definitionIn-addr.arpa
The DNS reverse-mapping domain for IPv4. Address octets are reversed as labels below in-addr.arpa, with zone boundaries aligned to delegated portions of address space.
Read definitionIn-bailiwick
A name that falls within the relevant zone or delegation boundary. A child name server whose name is inside the child zone normally requires glue in the parent.
Read definitionIndeterminate
A DNSSEC state in which a validator cannot determine whether data should be considered secure, insecure, or bogus, often because required information is unavailable or an unsupported algorithm is involved. Exact handling depends on the validating implementation and policy.
Read definitionIngress filtering
Filtering traffic entering a network based on whether the source address is plausible and authorized for that path. It helps stop spoofing and protects services from malformed or unexpected traffic.
Read definitionInheritance
The propagation of settings from a parent object, policy, network, or organizational level to child objects. DDI platforms use inheritance for options, ACLs, metadata, discovery settings, and service configuration.
Read definitionInline signing
A model in which an authoritative system accepts or stores unsigned zone data and automatically generates and serves the signed version. It separates content management from cryptographic signing operations.
Read definitionInsecure delegation
A delegation from a signed parent that intentionally has no DS record for the child, indicating that the child is not part of the DNSSEC chain of trust. Validators can accept the child's unsigned answers as insecure rather than bogus.
Read definitionInstance address
An address associated with a cloud compute instance or virtual network interface. It may be private, public, ephemeral, static, primary, secondary, or translated depending on the provider.
Read definitionInterface address
An IPv4 or IPv6 address configured on a network interface. A single interface can have multiple addresses, prefixes, scopes, and lifetimes.
Read definitionInterface ID
An identifier associated with a network interface. In IPv6, the more precise term Interface Identifier refers to the address bits following the subnet prefix; management systems may also use interface ID for an inventory key.
Read definitionInternal DNS
DNS infrastructure or data intended for an organization's internal clients and private namespaces. Internal DNS commonly supports recursion, private zones, Active Directory, service discovery, and split responses.
Read definitionInternet draft
A working document of the IETF that may change, expire, or never become an RFC. Draft features should be labeled clearly before production adoption.
Read definitionInternet Standard
An IETF maturity designation for a protocol specification with demonstrated value and stability. RFC 9915 is the current Internet Standard for DHCPv6 and is part of STD 102.
Read definitionIP address
A numeric identifier used by the Internet Protocol for routing and interface communication. IPv4 addresses are 32 bits and IPv6 addresses are 128 bits.
Read definitionIP address discovery
The process of finding addresses and devices in use through methods such as ping, ARP, Neighbor Discovery, SNMP, switch tables, cloud APIs, DNS, and DHCP leases. Discovery results should be reconciled rather than treated as perfect truth.
Read definitionIP address lifecycle
The stages through which an address or prefix moves, such as planned, reserved, assigned, active, discovered, quarantined, released, reclaimed, and archived. Defined lifecycle states make automation and audits safer.
Read definitionIP address plan
A documented design for allocating prefixes and addresses by site, environment, function, growth, routing boundary, and ownership. Good plans preserve summarization and leave room for expansion.
Read definitionIP helper
A router or switch feature that forwards selected UDP broadcasts, most commonly DHCPv4, to configured server addresses. Because some implementations forward multiple UDP services, the exact configuration should be reviewed.
Read definitionIP Source Guard
A switch feature that permits IP traffic on an access port only when it matches trusted bindings, often learned through DHCP snooping or configured statically. It helps block source-address spoofing.
Read definitionIp6.arpa
The DNS reverse-mapping domain for IPv6. Each hexadecimal nibble of the 128-bit address is reversed as a label beneath ip6.arpa.
Read definitionIPAM
IP Address Management, the discipline and tooling used to plan, allocate, assign, discover, reconcile, document, audit, and automate IP addresses and prefixes. Mature IPAM also links addresses to DNS, DHCP, devices, sites, owners, and workflows.
Read definitionIPAM reconciliation
Comparison of intended IPAM data with observed network, cloud, DNS, and DHCP state, followed by review or correction of differences. Reconciliation helps find stale, duplicate, unmanaged, and orphaned resources.
Read definitionIPAM utilization
The percentage or count of addresses and prefixes considered consumed within a container or subnet. Reports should distinguish assigned, leased, reserved, excluded, discovered, and unavailable states.
Read definitionIPv4
Internet Protocol version 4, using 32-bit addresses and a variable header. Private addressing, NAT, broadcast behavior, and address scarcity strongly influence IPv4 DDI operations.
Read definitionIPv4 link-local
Addresses from 169.254.0.0/16 that a host may self-assign for local-link communication when normal configuration is unavailable. They should not be routed.
Read definitionIPv4-mapped IPv6 address
An IPv6 representation of an IPv4 address in ::ffff:0:0/96, commonly used by APIs and dual-stack software. It does not by itself provide network translation.
Read definitionIPv6
Internet Protocol version 6, using 128-bit addresses, Neighbor Discovery, extension headers, and no broadcast. IPv6 addressing commonly combines Router Advertisements, SLAAC, DHCPv6, and prefix delegation.
Read definitionIPv6 address scope
The reachability boundary associated with an IPv6 address, such as interface-local, link-local, or global. Scope identifiers may be required when using link-local addresses on a multi-interface host.
Read definitionIPv6 prefix delegation
The assignment of an IPv6 prefix to a requesting router through DHCPv6 so it can number downstream links. It is widely used for broadband, branch, home, mobile, and delegated tenant networks.
Read definitionIPv6 Router Advertisement
An ICMPv6 message sent by routers to announce prefixes, default-router information, lifetimes, MTU, flags, and optional configuration such as recursive DNS. Hosts use it for on-link determination and often for SLAAC.
Read definitionIPv6 subnet
An on-link IPv6 prefix, conventionally /64 for ordinary LANs that use SLAAC and Neighbor Discovery. Different prefix lengths are possible for specific link types and designs.
Read definitionIPv6-only network
A network where endpoints are not assigned native IPv4 addresses. Access to IPv4-only services may be provided through NAT64, DNS64, 464XLAT, proxies, or application gateways.
Read definitionIRR
Internet Routing Registry, a collection of route and policy databases used to document intended routing relationships. IRR objects can support filtering but are distinct from RPKI cryptographic authorization.
Read definitionIterative query
A query for which the server returns the best answer or referral it currently has without taking responsibility for completing resolution on the client's behalf. Recursive resolvers send iterative queries to authoritative infrastructure.
Read definitionIterative resolution
The process of following referrals from the root, TLD, and lower authoritative servers until an answer or authoritative negative response is obtained. Results are cached according to TTL.
Read definitionIXFR
An incremental zone transfer that sends changes between SOA serial versions when both servers have suitable history. It can be much smaller than AXFR, with fallback to full transfer when needed.
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