Not using the DNS from your ISP is always a good practice and here is why.

Changing the DNS on your router is more convenient, as all devices connected to it within your network will be using the 3rd party DNS.

Windows

1. Right click on the network icon in System Tray and select Open Network and Sharing Center > Change adapter settings. Alternatively, you can open Control Panel > Network and Internet > Network and Sharing Center > Change Adapter Settings or you can open the Start menu and search for view network connections
2. Select the physical network adapter (wired or wireless) that you are using > right click on it > Properties
3. Open Internet Protocol Version 4 (TCP/IPv4)
4. Enable Use the following DNS server addresses and add the public DNS server(s) you want to use.

Mac OS X

1. Open System Preferences > Network
2. Select the active network adapter from the left column > Advanced...
3. Open the DNS tab, add the public DNS server(s) you want to use, press the Enter key to add them.

DD-WRT

1. Open Setup > Basic Setup
2. Enter the DNS servers as Static DNS. It is recommended to use 3.
3. Enable Use DNSMasq for DNS.
4. Save and Apply settings. Restart the router if needed.

Tomato and Tomato Advanced

1. Open Basic Settings > Network
2. Add the DNS servers under Static DNS. On Tomato Advanced, change DNS Server to Manual first.

pfSense

1. Open System > General Setup
2. Add the public DNS servers in DNS Servers section
3. Allow DNS server list to be overridden by DHCP/PPP on WAN must be unchecked
4. Do not use the DNS Forwarder as a DNS server for the firewall must be unchecked

On any other router, regardless of brand/model, the DNS settings are usually found in Network Settings or DHCP Settings.

DNS servers to use

• OpenDNS: 208.67.222.222 and 208.67.220.220
• Google: 8.8.8.8 and 8.8.4.4
• Level3: 4.2.2.1 and 4.2.2.2
• Hurricane Electric: 74.82.42.42
• In China, use OpenDNS servers (see above)