DNS (Domain Name System) is the process in mapping easy to remember domains names (google.com) to hard to remember IP addresses.
An IP (Internet Protocol) address is used for locating a server (or other device)
on the internet. Typically we see IPv4. An IPv4 address is composed of 4 bytes,
which is 32 bits, each byte is represented in a decimal number (up to 255),
for example 171.17.89.1. IPv4 has a total pool of 4,294,967,296 possible addresses.
IPv6 is a solution that will increase the pool to 3.4×10^38. An IPv6 addresses
are composed of 128 bits 2001:0db8:85a3:0000:0000:8a2e:0370:7334, represented
by 8 hexidecimal values seperated by colons.
An IP address is like a websites phone number, this is the number you input to contact the site. But no one wants to remember this number. So we map the number to a name (domain), like a phone book.
Domain names consist of many potential parts, broken down by hierarchy, each section
is separated by a ., domain hierarchy starts at the right most word, moving left.
The highest level of a domain is the TLD (top level domain) such as .com, moving
left we have a subcategory of the TLD, such as google, and to the left of this
is a subdomain, such as www. Almost any number of levels can exist.
ICANN (Internet Corporation for Assigned Names and Numbers) is responsible for
managing the TLD's (.com). ICANN is also responsible for authorizing domain name
registrars (such as GoDaddy™). Domain name registrars are in the business of registering
domain names and mapping the domain to IP addresses
So to register a domain we can use on of the domain registrars (hint: never use GoDaddy) My favorite for registration and configuration is http://dnsimple.com, but you might want to check out https://domai.nr/ as a tool to search for domains. Domains are priced from $0.99 up to millions, but typically run from $10-$50 depending on the TLD.
After purchasing a domain, you will use the domain registrars tools to manage the DNS configuration. There are many types of configurations:
NS (Name Server) records indicate who the authoritative name server is, when registering your domain with a registrar they will set the NS records to their own server. This means that any request to your domain will first contact their server to resolve the requested IP Address. Even when registering with a given registrar, you can change your NS records to any value you'd like.
A records are a direct mapping of a domain to an IPv4 address.
Maps a sub-domain to a different domain. This allows for an intermediary server to manage
where the domain is mapped to without having to assign a static IP address. For
instance Heroku is a cloud service, your IP address may change over time, but
we can add a CNAME for our domain to the .herokuapp name of our application, then
Heroku can manage the rest. The problem with CNAME records is that they can't map
to a root domain, they must map to a subdomain, such as www
Alias records are a combination of the above two, they are mappings between two domains. Alias records are not an industry standard yet. But, they are the solution for using cloud based services and root domains. Not many DNS providers support ALIAS records yet.
This is pretty simple, we're going to take our IP address and create an A record pointing pointing to the host name we want.
Each service has a different DNS setup, most will give you instructions for configuring your DNS records. Here are a couple of the guides: