[ipxe-devel] Fallback to IPv4 or disable IPv6

Michael Brown mcb30 at ipxe.org
Mon Nov 19 12:49:27 UTC 2018

On 19/11/2018 11:13, Andreas Fink wrote:
>> On 19 Nov 2018, at 11:52, Michael Brown <mcb30 at ipxe.org> wrote:
>> iPXE will query for AAAA records only if the DNS server address is itself an IPv6 address.  This is the heuristic we use to decide between IPv6 and IPv4 when a DNS name is used.
> This is not really what the idea is.
> I would recommend the following logic:
> <snip>

Yes, the logic is not guaranteed to work.  It is, as I stated, a 
heuristic.  It works in most common scenarios, and it avoids the code 
complexity required to handle reachability failures at the point of 
initiating the TCP connection.

We could potentially change the logic so that the DNS resolver always 
queries AAAA records first, but discards any results that are 
unreachable according to the IPv6 routing table.  Would this solve your 


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