Check conflicts and release addresses
05A client checks an offered address before use. Discovery of a conflict and voluntary release are different protocol messages.
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“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 4.4.1 ↗
RFC 2131 · § 4.4.1EXAMPLE
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03
Release a different valid lease voluntarily.
This is a separate example: a client that no longer needs its valid allocation returns it.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Do not quietly use an address already in use.
- After DHCPACK, a client should perform a final check such as ARP for the assigned address.
- A detected conflict requires DHCPDECLINE; the client should wait at least ten seconds before restarting allocation.
- DHCPRELEASE returns an address when it is no longer needed; it is not a conflict report.
RFC 2131 does not provide a complete secure address-ownership system. Duplicate checks and server-side conflict handling reduce errors but do not authenticate peers.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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