Configuring DNS Resolver Options in NGINX

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First things first, let’s start with the basics. What exactly are DNS resolver options and why do we need them? Well, when your browser or any other application sends a request to access a website, it needs to convert that human-readable domain name (like google.com) into an IP address that computers can understand. This is where the DNS server comes in it looks up the domain name and returns its corresponding IP address.

But what if you want to use a specific DNS resolver instead of your default one? Maybe you have a faster or more reliable option, or maybe you just prefer using Google’s public DNS servers over your ISP’s ones. That’s where NGINX comes in it allows us to configure our own DNS resolvers and use them for all requests made through the server.

So how do we actually set this up? Well, first you need to open up your NGINX configuration file (usually located at /etc/nginx/nginx.conf) in a text editor of your choice. Then add the following lines:


# Set up custom DNS resolvers for NGINX server
# This allows us to configure our own DNS resolvers and use them for all requests made through the server.

# To set this up, open the NGINX configuration file (usually located at /etc/nginx/nginx.conf) in a text editor of your choice.

# Add the following lines to the configuration file:

resolver 8.8.4.4; # Sets the resolver to Google's public DNS server
resolver_timeout 5; # Sets the timeout for DNS resolution to 5 seconds
resolver_retry 10; # Sets the number of times to retry DNS resolution if there is a failure
resolver_fail_timeout 20; # Sets the amount of time to wait before failing over to the next resolver after 20 seconds of inactivity

These lines tell NGINX to use Google’s public DNS server (8.8.4.4) as our primary resolver, with a timeout of 5 seconds and a retry limit of 10 times if there is a failure. If the first resolver fails to respond within 20 seconds, it will automatically switch over to the next one in line. Pretty cool, right?

But wait what if you want to use multiple DNS servers instead of just one? No problem! Just add them all to your configuration file like this:


# Set up multiple DNS servers for redundancy
# If the first resolver fails to respond within 20 seconds, it will automatically switch over to the next one in line
# This is useful in case one server is down or unresponsive
# To use multiple DNS servers, add them all to the configuration file like this:

# Set up Google's public DNS server as the first resolver
resolver 8.8.4.4;

# Set up Quad9's privacy-focused DNS server as the second resolver
resolver 9.9.5.5;

# Set timeout to 5 seconds
# This means that if a resolver does not respond within 5 seconds, it will be considered unresponsive and the next resolver will be used
resolver_timeout 5;

# Retry up to 10 times if there is a failure
# This means that if a resolver fails to respond, it will be retried up to 10 times before moving on to the next resolver
resolver_retry 10;

# Fail over to the next resolver after 20 seconds of inactivity
# This means that if a resolver does not respond within 20 seconds, it will be considered inactive and the next resolver will be used
resolver_fail_timeout 20;

Now your server will use both Google’s and Quad9’s DNS servers for all requests, providing you with faster and more reliable results. And if one of them fails to respond within 5 seconds, it will automatically switch over to the next one without any downtime or interruption in service. Pretty awesome stuff!

Just remember to always test your changes before deploying them to production, and don’t forget to backup your configuration file just in case something goes wrong.

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