DDI fundamentals8 min
What is DDI?
See how DNS, DHCP, and IPAM work as one operational system—and why managing them together matters.
Free DNS, DHCP & IPAM learning
Learn DNS, DHCP & IPAM.
See how each service works on its own—and how they operate together as DDI. Learn with practical lessons, trusted sources, and a searchable 753-term glossary.
6practical lessons
755terms and acronyms
Freeopen learning
Learn DDI
View every lesson Understand each service. Then see the system.
DDI fundamentals10 min
How DNS resolution works
Trace a lookup from the stub resolver through recursive and authoritative DNS, including caching and common failure points.
DDI fundamentals9 min
DHCP DORA and the lease lifecycle
Understand Discover, Offer, Request, Acknowledge—and what happens when a client renews, moves, or loses its lease.
Interactive tools
View every tool Work the problem, not just the definition.
IPv4 subnet calculator
Turn an IPv4 address and CIDR prefix into its network, mask, usable range, broadcast address, and subnet plan.
Open toolLive DNS record lookup
Query public DNS records and inspect the answer shape, TTL, priority, and authority data without leaving KnowDDI.
Open toolDHCP lease lifecycle simulator
Explore DORA, renewal at T1, rebinding at T2, and lease expiry under different server-response scenarios.
Open toolExplore the glossary
Find any term in seconds
24 starting points · 755 terms
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DDI
The integrated management and delivery of Domain Name System, Dynamic Host Configuration Protocol, and IP Address Management. A DDI platform connects naming, address assignment, inventory, policy, automation, and operational visibility.
Read full entryDNS
The Domain Name System, a distributed hierarchical database and protocol used to map names to resource records. It supports far more than address lookup, including service discovery, email routing, delegation, policy, and security data.
Read full entryDHCP
The Dynamic Host Configuration Protocol automatically supplies hosts with IP addressing and other configuration. DHCPv4 and DHCPv6 are separate protocols with different message formats, transports, identifiers, and state models.
Read full entryIPAM
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 full entryDNSSEC
DNS Security Extensions add origin authentication and integrity protection to DNS data through digital signatures and authenticated denial of existence. DNSSEC does not encrypt queries or responses.
Read full entryIPv4
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 full entryIPv6
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 full entryA record
An Address record maps a domain name to a 32-bit IPv4 address. It is one of the most common DNS data types and is normally used for forward name resolution.
Read full entryAAAA record
An IPv6 Address record maps a domain name to a 128-bit IPv6 address. The name is pronounced "quad A".
Read full entryCNAME record
A Canonical Name record makes its owner name an alias for a target name. With limited DNSSEC-related exceptions, other data should not coexist at the same owner name.
Read full entryPTR record
A Pointer record maps a reverse-domain name to another domain name, most commonly mapping an IPv4 or IPv6 address to a host name. Multiple PTRs are technically possible but can confuse applications.
Read full entryMX 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.
Read full entrySOA record
The Start of Authority record identifies key zone parameters including MNAME, RNAME, serial, refresh, retry, expire, and minimum fields. Every authoritative zone has an SOA at its apex.
Read full entryTime to live (TTL)
The number of seconds a DNS record may be cached before it must be treated as expired. TTL choices affect change speed, query load, resilience, and negative or stale-answer behavior.
Read full entryRecursive query
A query requesting that the server obtain a final answer or error on the client's behalf rather than returning only a referral. Recursion is requested with the RD bit and controlled by server policy.
Read full entryAuthoritative server
A DNS server that provides authoritative answers for one or more zones. It may obtain data from a primary source, a zone transfer, a database, a catalog, or a hosted control plane.
Read full entryDHCP lease
A time-limited authorization for a client to use an address or prefix together with associated configuration. The client renews before expiration or stops using the resource when the lease is no longer valid.
Read full entryDHCP relay agent
A router, switch, firewall, or server function that forwards DHCP messages between clients and servers on different links. It adds link-identifying information so the server can select the correct subnet or policy.
Read full entrySubnet
A prefix used as an on-link network or administrative allocation unit. In IPv4 it has a network mask and usually network and broadcast addresses; IPv6 LANs commonly use /64.
Read full entryCIDR
Classless Inter-Domain Routing, the use of variable-length prefixes rather than legacy address classes. CIDR notation combines an address with a prefix length, such as 10.20.0.0/16.
Read full entryDNS over HTTPS (DoH)
DNS carried in HTTPS, typically over TCP port 443. DoH provides transport confidentiality and server authentication while sharing web infrastructure and policy considerations.
Read full entryDNS over TLS (DoT)
DNS carried over a dedicated TLS connection, normally TCP port 853. It encrypts resolver traffic and authenticates the selected resolver when certificates are validated.
Read full entryReverse lookup
A query that converts an IP address into its reverse-domain name and requests a PTR record. The result is descriptive and does not by itself prove ownership or trust.
Read full entryDDNS
Dynamic DNS, the controlled creation, modification, or deletion of DNS records without manually editing a zone file. DHCP servers and clients commonly use DNS UPDATE to register address and pointer records.
Read full entry