If a router advertisement sends the range of subnet, and the client can choose an IP from it, how is there no conflict with another client that has chosen the same address?


1 Answer 1


A host performs Duplicate Address Detection (DAD) before actually activating the given address on the interface

RFC 2462 has to say about this:

5.4. Duplicate Address Detection

Duplicate Address Detection is performed on unicast addresses prior to assigning them to an interface whose DupAddrDetectTransmits
variable is greater than zero. Duplicate Address Detection MUST take
place on all unicast addresses, regardless of whether they are
obtained through stateful, stateless or manual configuration, with
the exception of the following cases: [...]

The original RFC was updated/modernized by RFC 4429 and further on by RFC 7527

EDIT To nitpick a bit: the correct sequence of RFCs is more precisely:

RFC 1971, obsoleted by RFC 2462, obsoleted by RFC 4862, updated by RFC 7527

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