MAC address
A link-layer hardware address, commonly 48 bits on Ethernet. DHCPv4 often uses it as part of client identity, but it can be changed, duplicated, or hidden behind relays.
Read definitionAlphabetical glossary
M glossary terms
18 definitions beginning with M.
18 terms
Managed address configuration flag (M flag)
A Router Advertisement flag indicating that hosts should use DHCPv6 for stateful address configuration. Host behavior can vary by operating system and network policy.
Read definitionManaged DNS
A DNS service operated by a provider or centralized platform on behalf of the zone owner. Management, signing, distribution, scaling, and availability are delivered through a service control plane.
Read definitionManagement plane
The interfaces and systems administrators use to configure, observe, audit, and automate DDI services. Compromise or outage of the management plane can be serious even when data-plane service continues.
Read definitionManual allocation
An allocation method in which an administrator preassigns a specific address to a client and DHCP communicates that assignment. It is commonly implemented through reservations or fixed mappings.
Read definitionMartian address
An address that is invalid or unexpected in a particular routing context, such as a loopback or private source arriving from the public Internet. The classification depends on interface, direction, and policy.
Read definitionMaster file
The standardized text representation of DNS zone data, also called zone-file format. Modern terminology favors primary and secondary for server roles rather than master and slave.
Read definitionMaximum client lead time (MCLT)
A DHCP failover safety interval limiting how far one partner can extend a lease beyond information known to the other. It reduces the chance of duplicate allocation after communication or partner failure.
Read definitionMaximum DNS message size
DNS over UDP was originally limited to 512 bytes, while EDNS allows larger advertised payloads. DNS over TCP and other stream transports can carry messages up to 65,535 bytes, subject to protocol framing and implementation limits.
Read definitionmDNS
Multicast DNS resolves names and discovers services on a local link using multicast and the .local special-use domain. It is separate from unicast enterprise DNS even though it uses DNS message formats.
Read definitionMetadata
Descriptive attributes associated with DDI objects, such as owner, site, application, environment, status, ticket, or cost center. Consistent metadata enables automation, search, reporting, and governance.
Read definitionMicrosoft DHCP
The Windows Server DHCP role for IPv4 and IPv6 configuration, scopes, reservations, policies, authorization, DNS updates, and DHCPv4 failover. Management is available through GUI, PowerShell, and APIs.
Read definitionMicrosoft DNS
The DNS Server role and related client components in Windows Server and Active Directory environments. It supports AD-integrated zones, secure dynamic update, conditional forwarding, policies, DNSSEC, and standard DNS protocols.
Read definitionMNAME
The first domain-name field in the SOA record, conventionally naming the zone's primary source server. Modern distributed and hidden-primary architectures can make the literal operational role more nuanced.
Read definitionMonitor
A health-check definition used to determine whether a server or service is available. Monitors may run from one or multiple locations and can test transport, application content, or dependency health.
Read definitionMulti-primary
An architecture in which more than one authoritative source can accept changes for the same zone and a separate replication system reconciles them. Active Directory-integrated DNS is a common example.
Read definitionMulticast
Delivery from one sender to a group of interested receivers. IPv6 replaces IPv4 broadcast with multicast for many functions, and DHCPv6 clients use well-known multicast destinations to reach servers or relays.
Read definitionMX record
A Mail Exchange record identifies mail servers for a domain and assigns each a preference value. Lower preference values are tried first, with equal values treated as alternatives.
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