On Jan 18, 2008, at 11:19 PM, [EMAIL PROTECTED] wrote:
What happens when your DHCP lease expires? The duration of a lease isn't that long so it must happen often.
I'm just going from memory here, but the RFCs and DHCP server documentation would be authoritative sources.
When a DHCP lease approaches expiration (there's some lead-up time), the client should re-ask for the same IP address again, effectively extending the lease on the current IP address for another period. The server has the option of simply acknowledging the request or saying no.
If the server says yes, everything keeps on as normal.If the server says no, the client must re-submit a fresh request, asking for any available IP address which it can lease. Now, the server may give it a new lease, or still say no.
If the server gives a new lease, the client reconfigures itself as required by the new lease.
If the server just says no, the client is supposed to release the current lease at the end of the expiration, and remain unconfigured. It should then continue to query for a new lease periodically.
Many ISPs (using DSL and Cable as an example) will happily let you keep your IP address as long as you're connected, and will frequently keep your lease reserved for some period of time even after you disconnect (i.e., beyond the DHCP lease expiration.) ISPs generally won't reject a lease renewal on an already-connected system, as it would prove too disruptive to any existing network communications for that system.
Gregory -- Gregory K. Ruiz-Ade <[EMAIL PROTECTED]> OpenPGP Key ID: EAF4844B keyserver: pgpkeys.mit.edu
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