APIPA
Embed This Widget
Add the script tag and a data attribute to embed this widget.
Embed via iframe for maximum compatibility.
<iframe src="https://ipfyi.com/iframe/glossary/apipa/" width="420" height="400" frameborder="0" style="border:0;border-radius:10px;max-width:100%" loading="lazy"></iframe>Paste this URL in WordPress, Medium, or any oEmbed-compatible platform.
https://ipfyi.com/glossary/apipa/Add a dynamic SVG badge to your README or docs.
[](https://ipfyi.com/glossary/apipa/)Use the native HTML custom element.
정의
자동 사설 IP 주소 지정(Automatic Private IP Addressing). DHCP 서버를 사용할 수 없을 때 장치가 169.254.0.0/16 범위에서 IP 주소를 자동으로 할당하는 메커니즘입니다. APIPA 주소는 로컬 링크 통신은 가능하지만 로컬 서브넷을 넘어 라우팅되지 않습니다.
How APIPA Works
When a host running Windows or another APIPA-capable OS fails to receive a DHCPDynamic Host Configuration Protocol. A network protocol that automatically assigns IP addresses, subnet masks, gateways, and DNS servers to devices when they join a network. lease — because the server is unreachable or the network has no DHCP server — it automatically self-assigns an address in the 169.254.0.0/16 range. The host first sends ARP probes to verify the chosen address is not already in use on the segment, then configures the interface. This process is also defined in RFC 3927 as IPv4 Link-Local.
Scope and Limitations
APIPA addresses are strictly Link-Local AddressAn IP address valid only within a single network segment, automatically configured without DHCP. IPv4 uses 169.254.0.0/16 (APIPA) and IPv6 uses fe80::/10 for neighbor discovery and local communication.: routers will never forward packets sourced from or destined for the 169.254.0.0/16 range. This means APIPA-configured hosts can communicate only with other APIPA hosts on the same Layer 2 segment — they cannot reach the internet, DNSDomain Name System. The hierarchical, distributed naming system that translates human-readable domain names (e.g., example.com) into IP addresses (e.g., 93.184.216.34). Often called the "phonebook of the internet." servers, or any device on a different subnetA 32-bit number (e.g., 255.255.255.0) that divides an IP address into network and host portions. It determines which part of the address identifies the network and which part identifies individual devices.. Spotting 169.254.x.x addresses in a network scan is a reliable indicator that DHCP acquisition failed on those hosts.
Diagnostic Value
Network engineers treat APIPA as an early-warning signal. If a large number of devices in a VLAN self-assign 169.254.x.x addresses simultaneously, the DHCP server has likely crashed, the DHCP scope has been exhausted, or a rogue device is rejecting OFFER packets. Checking for APIPA is a standard first step in LAN troubleshooting before escalating to DHCP server logs. Subnet Calculator