Is it possible to use nsupdate with EDNS0?

[Mark Andrews]

While legal it is most definitely not a good idea. You first have to probe to find out the EDNS buffer size. Then you may also need to deal with PMTUD issues.  The you need to deal with broken middle boxes and fragmentation. Dealing with all of this is done at the application level. Add to that TCP still needs to be supported on the server anyway there really is no point in trying. 

Named does not attempt to send larger than 512 byte updates via UDP.  There are no plans to do so. 
-- 
Mark Andrews

> On 17 Jan 2019, at 00:14, Fumiya Obatake <fobatake at gmail.com> wrote:
> 
> Is it possible to use nsupdate with edns0?
> 
> Hello, all.
> I have some questions about nsupdate.
> 
> I try to update a set of TXT records over 512 bytes in all by using
> nsupdate without -v option, and it makes TCP connection automatically.
> In RFC2136, `An update transaction may be carried in a UDP datagram,
> if the request fits, or in a TCP connection (at the discretion of the
> requestor).`, so I guess this behavior is due to the not fitting
> request packet (since over 512 bytes).
> But RFC6891, EDNS0, should be able to use over 512 bytes DNS message.
> I think this is applicable to DNS update, but no one refers to it as
> far as I can see.
> 
> My question is:
> 1. Does it violate RFC2136 to use EDNS0 with DNS Update?
> 2. If not, does BIND have any plan to implement nsupdate with EDNS0?
> 3. Or, is any other solution to update over 512 bytes message by UDP?
> 
> Best regards,
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