[Dnsmasq-discuss] Modification to the feature of config-static DNS record in dual-stack network.

Simon Kelley simon at thekelleys.org.uk
Mon Nov 29 21:56:05 GMT 2010


On 27/11/10 04:08, 许伟林 wrote:
> It works!
> 
> Frankly speaking, it is a bit troublesome for me to double the 
> config-items. You see large websites, such as youtube.com 
> <http://youtube.com>, store resources (images, caches and etc.) in 
> different domains and hosts. I have to add dozens items for youtube.com 
> <http://youtube.com>.

There's no way that I can change the default behaviour; the only other
solution would be a flag that changed this for all domains. That's less
flexible (you might not want to change it for all domains)

> 
> Actually I suppose my modification is OK too.
> 
> Two things we need to realise are that
> 1) The browser won't send an AAAA DNS query if user's host don't support 
> IPv6;
> 2) The upstream nameserver will return an empty AAAA record if the 
> network operator doesn't deploy IPv6.
> 
> As a result, if we put an item
> --address = /<domain>/<IPv4 address>
> on the config file, the browser's IPv6-first behavior won't trouble users:
> 1) If the host don't support IPv6, no AAAA query will be sent;
> 2) If the network operator hasn't deploy IPv6, the response of empty 
> AAAA record won't affect the web access. Else, users can access the 
> Internet through IPv6. Users will happy to do that since the IPv6 
> network is usually faster and cheaper.
> 
> But considering the actual situation, your scheme is better. Users 
> usually cannot access IPv6 even if the network operator has deploy it 
> since most NAT-router don't support IPv6. What's more, some others may 
> use dnsmasq on the other situation except NAT-router.
> 

There's a problem with domains that don't exist in the global DNS.

if I do

--address=/host.simon/1.2.34

and a browser does an IPv6 lookup of host.simon, if that's passed to an
ordinary DNS server the answer will be NXDOMAIN. A sensibe resolver will
not then do an IPv4 lookup (The domain doesn't exist, right) so the
lookup won't work right. The only way to make this work is to return
NODATA for IPv6 lookups of host.simon.


Cheers,

Simon.



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