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How can I change my DNS server from the Terminal on Mac OS X? [I need this because my DNS is not working correctly with my VPN. Sometimes it's using the DNS for my main connection, and sometimes it's using the DNS specified for the VPN (which it should).]

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up vote 9 down vote accepted

You can use scutil interactively from the terminal. Run sudo scutil and run these commands, swapping your DNS servers in where appropriate:

> open
> d.init
> d.add ServerAddresses * 8.8.8.8 9.9.9.9
> set State:/Network/Service/PRIMARY_SERVICE_ID/DNS
> quit

Instead of using 8.8.8.8 and 9.9.9.9 use your DNS servers.

The only problem is this is not persistent across reboots. If you want permanent changes, you'll want ncutil. The reason editing /etc/resolv.conf isn't sufficient in newer versions of OS X is because configd now uses a database to store information of current settings, which other applications read. Certain applications will still read /etc/resolv.conf (host for example), although that is not the case for all applications.

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2  
8.8.8.8 is a valid one, though. Google's Public DNS. 8.8.4.4 is the secondary. :-) – Forgotten Semicolon Dec 21 '09 at 19:03
    
I know, I use it :) – John T Dec 21 '09 at 19:11
1  
It should. You can use scutil --dns to confirm. – John T Dec 21 '09 at 19:21
2  
This does not seem to work on my Mac OSX 10.7.5 MBP, at least not when done literally. Should I replace anything in the set State:/Network/Service/PRIMARY_SERVICE_ID/DNS line or can I use that as it is ? Should the new DNS servers show up in the scutil --dns output after the change ? – ssc Oct 30 '13 at 13:57
1  
@ssc Run scutil followed by > list to find the key to replace PRIMARY_SERVICE_ID with. – J.Money Mar 31 '15 at 2:12

You can use networksetup:

sudo networksetup -setdnsservers <networkservice> DNS1, DNS2, DNS3

eg (having the Airport connection use Google's DNS Servers)

sudo networksetup -setdnsservers AirPort 8.8.8.8 8.8.4.4

You can find out the name of the network service by running networksetup -listallnetworkservices. It'll be 'Wi-Fi' probably.

This is the same as if you were to edit the entires in the Network Preference Pane in System Preferences, so it is persistent across reboots.

You may be running into a DNS issue on Snow Leopard that occurs when the order DNS servers are queried changes (see question 84144))

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Wow, 84144 is the problem I'm having. Still processing all of this.... thank you muchly! – Dan Rosenstark Dec 21 '09 at 21:52
    
Thanks for clear and understandable answer :) – nXqd May 31 '12 at 7:24
    
+1 works beautifully, thank you. – jackJoe Nov 29 '12 at 9:14
3  
One note to anyone wanting to remove the DNS, just write "empty" (without the quotes) instead of the DNS: sudo networksetup -setdnsservers <networkservice> empty – jackJoe Nov 29 '12 at 9:36

I don't have enough points to reply to Chealion's post but to add on to it I'd start with listing the interfaces

networksetup -listallnetworkservices

Once you have the interface you'd like to change you can do the below (I'm using the Wi-Fi but you can do any other interface)

sudo networksetup -setdnsservers Wi-Fi empty
sudo networksetup -setdnsservers Wi-Fi 8.8.8.8 8.8.4.4
sudo killall -HUP mDNSResponder

The first line of the above will empty out the DNS settings then follow it with the DNS servers we'd like to use and finely clear the DNS cache

To verify the DNS change you can do this before and after or simply after

scutil --dns | grep 'nameserver\[[0-9]*\]'
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You should be able to do it by editing /etc/resolv.conf (remember resolv.conf is reset after reboot), hope it helps - http://developer.apple.com/mac/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html

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4  
As of older versions of OS X (10.2 and prior), that is the way to go. Not with newer releases though. – John T Dec 21 '09 at 19:06
    
Thanks for that. Unfortunately, I'm in 10.6.2. – Dan Rosenstark Dec 21 '09 at 19:15

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