[Dnsmasq-discuss] Does dnsmasq support forwarding EDNS queries?

[Jake Gold]

Hello,

I'm using dnsmasq as a local caching resolver and some of my queries result
in large answers (~1300 bytes) that are truncated without EDNS.

When I query my local dnsmasq daemon:

dig @localhost <record.with.big.answer>

dig sends a query to dnsmasq using EDNS but dnsmasq forwards that query to
its upstream server without using EDNS.

Is this just how dnsmasq works or is there a way to make dnsmasq forward
EDNS queries? (Or am I missing something?)

Thanks in advance.

-Jake

[Simon Kelley]

Post by Jake Gold
Hello,
I'm using dnsmasq as a local caching resolver and some of my queries result
in large answers (~1300 bytes) that are truncated without EDNS.
dig sends a query to dnsmasq using EDNS but dnsmasq forwards that query to
its upstream server without using EDNS.
Is this just how dnsmasq works or is there a way to make dnsmasq forward
EDNS queries? (Or am I missing something?)
Thanks in advance.

EDNS (in this context) is a way for the two ends of a DNS transaction to
negotiate the maximum size of reply that can be sent over UDP. Dnsmasq
will not strip an EDNS header from a query it forwards, but it might
reduce the "maximum UDP size" field, based on the config setting
--edns-packet-max.


In the end, if an answer is too big, the query has to be re-done over
TCP. A common problem with this is firewalls which block port 53 for TCP.


Cheers,

Simon.