DNS server order IPv6/IPv4

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ogawa9 Author

Level 1

27 points

DNS server order IPv6/IPv4

Some times ago, MacOS changes the priority of DNS server, I believe, that

MacOS first tries to connect to DNS server that in IPv6 space, then if fails tries to connect to DNS server of IPv4.

I get DNS server infomation in system pref. network pane DNS servers field from DHCP (and IPv6 RA) like this:

10.0.1.127

240b:10::a

(note: those addresses are false. just for examples)

but my Mac asks to resolve a host name to 240b:10::a first.

"scutil --dns" shows the same result (IPv6 first, IPv4 next)

How can I reverse the priority? or make Mac to obey the listing order.

note, I use DHCP, not set these DNS servers manually. this is the condition.

iMac with Retina 5K display, macOS High Sierra (10.13.2), DELL 4K display

Posted on Jan 12, 2018 2:08 PM

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Answer 1

ogawa9 Author

Level 1

27 points

Jan 12, 2018 3:34 PM in response to dot.com

As I mentioned, I wouldn't input DNS server. this is definite condition of this question. All must be provided from DHCP and RA.

In that condition, IPv6 is first. This is fact.

In my Mac, resolver ask IPv6 addressed DNS server first, and then the server (ISP provides) answered my private domain, so Mac can't resolve it.

my private domain's domain master is 10.0.1.127 and it also forwards to upper servers.

The list show as I wrote, IPv4 server is first. But IPv6 server is asked first. because,

scutil --dns

shows like this in spite of the pane order:

240b:10::a

10.0.1.127

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Answer 2

dot.com

Level 4

2,455 points

Jan 12, 2018 2:43 PM in response to ogawa9

The priority of DNS resolvers is whatever is in the DNS servers list in the Advanced Options DNS tab. I modified my order and then did the "scutil --dns" afterwards and the order reflects the order in that pane. I'm guessing that because you're in a mixed IPV4/IPV6 environment, that if you invert your list of DNS servers in the Advanced pane, you will get what you're looking for? I'm also guessing that IPV6 addresses would get sent to the IPV6 DNS server and IPV4 addresses get sent to the IPV4 server, but I don't do anything with IPV6 so can't verify.

Even if you use DHCP you can manually specify DNS servers - I think so anyway. Won't hurt to try it.

Good luck...

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