Label
A component of a domain name separated by dots in presentation form. On the wire, a standard label is length-prefixed and generally limited to 63 octets.
Read definitionAlphabetical glossary
L glossary terms
23 definitions beginning with L.
23 terms
Lame delegation
A delegation that points to a server that is not authoritative for the delegated zone or cannot serve it correctly. Lame delegations cause resolution delays, intermittent failures, and operational noise.
Read definitionLast known good
A previously validated configuration or data state retained for rollback or recovery. DDI changes should define how to restore a last-known-good zone, database, or service configuration.
Read definitionLease
The time-bounded right for a client to use an address or prefix and associated configuration. Lease state is maintained by both client and server.
Read definitionLease database
The server data store containing lease bindings, states, identities, and timing. Backup, replication, integrity, and recovery of this database are central to DHCP availability.
Read definitionLease duration
The amount of time an address or prefix remains valid before renewal or expiration. Short leases increase churn and server traffic, while long leases slow reclamation and configuration change.
Read definitionLease history
A record of past address-to-client associations and state changes. It supports troubleshooting, security attribution, capacity analysis, and compliance retention.
Read definitionLease reclamation
The process of returning expired, released, or administratively cleared addresses to an available state. Reclamation may include grace periods, conflict checks, DNS cleanup, and history retention.
Read definitionLeasequery
A protocol family that allows authorized systems to request current or historical binding information from DHCP servers. It is used by relays, access concentrators, security platforms, and IPAM systems.
Read definitionLeast-specific route
The route with the shortest matching prefix length. When no more-specific route exists, traffic follows the least-specific matching route, often the default route.
Read definitionLink
A communication domain on which nodes can exchange IP packets without an intervening router. DHCPv6 and Neighbor Discovery use link identity rather than IPv4-style broadcast domains.
Read definitionLink-address
A field in a Relay-forward message used to identify the client link to the DHCPv6 server. The server uses it to select appropriate address or prefix pools and options.
Read definitionLink-local address
An address valid only on the local link and not routed beyond it. IPv6 link-local unicast uses fe80::/10, while IPv4 link-local uses 169.254.0.0/16.
Read definitionLLA
Common abbreviation for IPv6 link-local address. Every IPv6-enabled interface generally has one, and routing protocols and Neighbor Discovery frequently use it.
Read definitionLLMNR
Link-Local Multicast Name Resolution, a multicast protocol for resolving names on a local link when DNS is unavailable. It is not DNS, can create security exposure, and is often disabled in managed environments.
Read definitionLoad balance
A failover mode or traffic design in which multiple servers actively handle clients according to a hash, split, relay selection, or load balancer. For DHCP, shared lease state and consistent client handling are critical.
Read definitionLOC record
A Location record encodes geographic coordinates, altitude, size, and precision for a domain name. It is not widely deployed and should not be relied on as a current asset-location system.
Read definitionLocal data
DNS records or policy answers configured directly in a resolver rather than learned from public authoritative resolution. Examples include local zones, hosts entries, block responses, and internal overrides.
Read definitionLocal zone
A resolver-controlled zone that provides authoritative-like local answers, negative responses, redirects, or policy for a selected namespace. It does not necessarily exist in the global DNS hierarchy.
Read definitionLocal-host zone
A locally served namespace used for host-specific or network-specific answers, often to override external data or provide private names. The term and exact semantics vary by resolver implementation.
Read definitionLongest-prefix match
The routing rule that chooses the matching route with the greatest prefix length. It explains why a more-specific route overrides an aggregate or default route.
Read definitionLoopback address
An address that routes traffic back to the local host. IPv4 uses 127.0.0.0/8 and IPv6 uses ::1/128.
Read definitionLow-water mark
A threshold indicating that available address capacity has fallen below a desired reserve. It can trigger alerts, expansion, or automated allocation from a parent block.
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