[ipxe-devel] Telling iPXE to only take certain DHCP offers

Michael Brown mbrown at fensystems.co.uk
Fri May 6 17:53:20 BST 2011

On Friday 06 May 2011 15:15:59 Greg Jednaszewski wrote:
> I have a similar situation, but I don't always have control over the DHCP
>  servers in question.  Can you describe what iPXE does when it receives
>  responses from multiple DHCP servers?  If it doesn't see the option 175
>  priority setting, does it just pick the first one it got?  Or is there
>  some other ordering it uses?

There is no defined ordering between equal-priority DHCP offers.

> Also, while looking at this issue, I came across the use-cached option. 
>  How does that work?  Is it possible to reuse dhcp information from the
>  original PXE rom DHCP query?  e.g.:
> PXE rom issues DHCP request
> DHCP server responds with IP address, filename, and next-server
> iPXE loads and reuses the cached info from the previous step

Yes, this should be possible.  In most cases it's unlikely to be what you 
want, since the original DHCPDISCOVER will not have requested options that may 
be meaningful to iPXE (such as the SAN root-path).


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