When we want to call a contact on our phone, all we have to do is click on their name. Within a single click, we’re calling the person.
Something similar happens when we go to a website online. All we need to do is enter the site’s name, and we’ll be led right to it. But just like your phone, the internet works with numbers, not names. Behind each site’s name, also known as the domain name, is an IP address where the website is hosted.
But who keeps track of all the IP addresses and the domain name they belong to, and how do you connect your domain back to your email account?
That’s what DNS is for!
Domain Name System
DNS stands for Domain Name System. This is how computers store your website information and allows you to interact with that information in a human way. The easiest way to understand this system (often referred to as “the phonebook of the internet”) is to compare how these systems work to your home address.
You have a mailing address, in addition to a lot number registered with the county. The mailing address is useful because it’s easily digestible by humans, but the lot number is useful because it’s digestible by computers. At the end of the day, they both point to the same location in a different way.
Whenever you enter a domain name in your browser (mailing address), the browser will find out what IP address belongs to it (lot number) so it can bring you the site.
What does this have to do with email?
When you think of a DNS server as a phonebook for identifying your website, you can probably start to see why email systems also operate through DNS.
Although it’s not quite as simple as setting up a website and *poof* you now receive an email, there are a few extra steps to take in order to send and receive an email to your domain. These steps will involve adding records to your DNS called “Mail Exchange” records (MX Records). These MX records are what build the bridge which allows you to communicate between your DNS and other DNS servers.
Build it, and they will come… Take advantage of it
Over time there have been many people who have found ways to abuse DNS systems. Since everyone uses these systems, it’s a big target for nefarious actors across the worldwide web.
This is why you will see many DNS systems have a focus on their security, and this is also the reason why email requires a few extra steps in order to verify that your “communication bridge” is only being used by the intended persons.
By adding verification records to your DNS server, you’re showing other DNS servers that you have security checkpoints, which gives the other DNS servers a sense of comfort that your bridge is safe to connect to.
Now, for the technical stuff…
What is a “recursive DNS”?
The recursive DNS server first checks its cache memory to see if the IP address (lot number) is already stored somewhere. If the IP address is already in the server’s memory, the recursive DNS server will immediately provide the IP address to your browser, and you will be taken to the site.
If the recursive DNS server does not have the IP address in its memory, it will start sending requests to “authoritative” DNS servers to fetch the IP address. Once it finds it, the recursive DNS server returns the IP to the browser, and the browser will bring the user to the requested site.
This process happens so quickly that you have no clue it’s happening.
Domain Host, DNS, Nameservers – What’s the difference?
A domain host is commonly confused with a DNS. It can offer DNS services, but it is different.
A domain host service is what manages your domain name, such as example.com. Most domain name registrars provide default DNS services along with the cost of domain registration. This means in most cases, DNS records are managed by the registrar and its standard nameservers when you first sign up.
A nameserver is what identifies where your DNS is hosted. If you buy a domain from a Domain Host, but you want to start using a different DNS server, you can set up custom nameservers to make this change. Custom nameservers also allow you to manage your own nameserver and provide a backup if an issue occurs with other nameservers and many other security features that the domain host may not have.
For most users starting off with their first website, this isn’t necessary to worry about right away.
DNS propagation is the time period needed for updates to DNS records to be in full effect across all servers on the web. Changes aren’t instantaneous because, as mentioned before, servers will temporarily store domain record information in their cache to help things load quicker.
Each DNS record has a time-to-live (TTL) value. When a caching (recursive) nameserver handles a request from an authoritative nameserver for a record, it will cache that record for the time specified by the TTL.
When you look at your DNS and see “TTL” with a value of 3600, that is telling servers across the web “check every 3600 seconds (1 hour) for updates to the record”. If you want to revert a mistake quickly, you can set a shorter TTL to have changes take effect quicker. Google recommends setting a TTL value of 86400 once your site configuration is successfully completed.
DNS serves a critical role as the backbone of the internet. Without DNS, you wouldn’t be able to access websites with ease, or communicate with your colleagues and partners. Ready to dive into the specifics of DNS records? Check out this article.
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