In message <[email protected]>, Fred Morris 
writes:
> I just noticed that when configuring firewall rules for an AWS instance,
> if "DNS" is chosen then the (only) protocol automagically filled in is
> UDP.
> 
> To get TCP, you have to create a custom TCP rule.
> 
> When you save, the UDP one gets saved as "DNS", the TCP one stays "custom
> TCP rule".

And the filtering rules break EDNS version negotiation.  The
nameservers themselves also need to be fixed to properly respond
to unknown EDNS versions (i.e. return BADVERS rather than ignore
the version in the request).

e.g.

9gag.com. @205.251.193.152 (ns-408.awsdns-51.com.): dns=ok edns=ok 
edns1=status,version,soa edns@512=ok ednsopt=ok edns1opt=status,version,soa 
do=ok ednsflags=ok
9gag.com. @205.251.197.14 (ns-1294.awsdns-33.org.): dns=ok edns=ok 
edns1=timeout edns@512=ok ednsopt=ok edns1opt=timeout do=ok ednsflags=ok
9gag.com. @205.251.198.137 (ns-1673.awsdns-17.co.uk.): dns=ok edns=ok 
edns1=status,version,soa edns@512=ok ednsopt=ok edns1opt=status,version,soa 
do=ok ednsflags=ok
9gag.com. @205.251.194.117 (ns-629.awsdns-14.net.): dns=ok edns=ok 
edns1=status,version,soa edns@512=ok ednsopt=ok edns1opt=status,version,soa 
do=ok ednsflags=ok
 
> --
> 
> Fred Morris
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: [email protected]
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