DNS settings

MacOS #

Refresh DNS #

To flush the local DNS cache:

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

Set DNS to Cloudflare #

To set the DNS to Cloudflare’s 1.1.1.1:

sudo networksetup -setdnsservers Wi-Fi 1.1.1.1 1.0.0.1 2606:4700:4700::1111 2606:4700:4700::1001

sudo networksetup -setdnsservers "USB 10/100/1000 LAN" 1.1.1.1 1.0.0.1 2606:4700:4700::1111 2606:4700:4700::1001

To revert the setup:

sudo networksetup -setdnsservers "Wi-Fi" empty

sudo networksetup -setdnsservers "USB 10/100/1000 LAN" empty

To see what DNS service the connection is using:

$ nslookup google.com
Server:		1.1.1.1
Address:	1.1.1.1#53

Non-authoritative answer:
Name:	google.com
Address: 172.217.21.238

Split DNS #

Source: https://gist.github.com/dferg/0472269333be4aca6aaa21cf3b165c02

Sometimes you may want to use a DNS server for specific domain requests and another DNS server for all other requests. This is helpful, for instance, when connected to a VPN. For hosts behind that VPN you want to use the VPN’s DNS server but all other hosts you want to use Google’s public DNS. This is called “DNS splitting.”

Here, we run dnsmasq as a background service on macOS. The dnsmasq configuration described below implements DNS splitting.

Install via Homebrew:

brew install dnsmasq

Edit $(brew --prefix)/etc/dnsmasq.conf:

# Ignore /etc/resolv.conf
no-resolv

# For queries *.domain.com and *.domain.net, forward to the specified DNS server
# Servers are queried in order (if the previous fails)
# -- Note: These are EXAMPLES. Replace with your desired config.
server=/domain.com/domain.net/IP_ADDR_OF_SERVER1
server=/domain.com/domain.net/IP_ADDR_OF_SERVER2

# Forward all other requests to Google's public DNS server
server=8.8.8.8

# Only listen for DNS queries on localhost
listen-address=127.0.0.1

# Required due to macOS limitations
bind-interfaces

Start the service:

sudo brew services start dnsmasq

Point to the new local DNS server:

sudo networksetup -setdnsservers "Wi-Fi" 127.0.0.1

sudo networksetup -setdnsservers "USB 10/100/1000 LAN" 127.0.0.1

Uninstall dnsmasq #

sudo brew services stop dnsmasq
brew uninstall dnsmasq
rm "$(brew --prefix)/etc/dnsmasq.conf"
sudo networksetup -setdnsservers "Wi-Fi" empty