HA pair
Two nodes configured as a high-availability unit, normally presenting a shared service identity and synchronizing state. Infoblox NIOS HA pairs use active and passive nodes with HA communication and service VIP behavior.
Read definitionAlphabetical glossary
H glossary terms
18 definitions beginning with H.
18 terms
Happy Eyeballs
A client connection strategy that quickly races or sequences IPv6 and IPv4 attempts so users are not delayed by a broken path for one family. It affects how A and AAAA answers translate into observed connections.
Read definitionHash algorithm
The cryptographic digest function used in DNSSEC operations such as DS records or NSEC3 hashing. Algorithm agility allows older digest methods to be replaced as security expectations change.
Read definitionHealth check
An active or passive test used to decide whether an endpoint should receive traffic. GSLB systems may monitor TCP, HTTP, DNS, application content, or external telemetry before publishing an answer.
Read definitionHeartbeat
A periodic signal used to show that a node, peer, or service is alive and communicating. Missing heartbeats can trigger alarms, state changes, or failover.
Read definitionHidden primary
A primary authoritative server that is not listed in the zone's public NS RRset and is normally reachable only by secondaries or management systems. It centralizes updates while reducing public exposure.
Read definitionHigh availability (HA)
A design objective and set of mechanisms that reduce service interruption when components fail. HA can include redundant nodes, state replication, anycast, routing convergence, secondary zones, and tested recovery procedures.
Read definitionHigh-water mark
A configured or observed utilization threshold indicating that an address pool or resource is approaching exhaustion. Alerts should leave enough time to expand, reclaim, or redesign the pool.
Read definitionHINFO record
A Host Information record that can describe CPU and operating system text for a host. It is rarely used on the public Internet because the information can become stale or reveal unnecessary detail.
Read definitionHold-down timer
A waiting period during which a resource, route, lease, or state transition is not immediately reused or reversed. Hold-downs reduce flapping and allow stale information to age out.
Read definitionHost
A network-connected system that originates or terminates traffic. In DNS usage, "host" is informal and should not be assumed to mean that every domain name has an address record.
Read definitionHost address
An IP address assigned to an interface or node for unicast communication. In IPv4 subnet calculations, host addresses traditionally exclude the network and broadcast addresses.
Read definitionHost bits
The bits of an address not covered by the network prefix. They identify addresses within the subnet and determine the number of possible interface addresses.
Read definitionHost record
A composite Infoblox IPAM object that can associate a host name with IPv4 or IPv6 addresses and optionally manage related A, AAAA, PTR, alias, or DHCP data. It is not a standard DNS resource record type.
Read definitionHostname
A name used to identify a host, often a single label or an FQDN. Hostname syntax rules are more restrictive than the full range of labels permitted by the DNS protocol.
Read definitionHot standby
A DHCP failover mode in which one server normally owns most or all active service while the partner is ready to take over. It is often chosen when servers are in separate sites or one is intended mainly for disaster recovery.
Read definitionHTTPBoot
A network boot method that retrieves boot resources using HTTP or HTTPS instead of TFTP. DHCP options identify client architecture and provide a boot URI or discovery information.
Read definitionHTTPS record
The HTTPS service binding record, a specialized SVCB form for HTTPS endpoints. It can advertise alternative endpoints, protocols, ports, encrypted-client-hello parameters, and address hints.
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