DNS: Roadmap of the Internet
DNS or "Domain Name System" is the glue that keeps the internet together. At its base level, DNS is the naming system for internet-connected resources. Without it your Google searches wouldn't load the page, Netflix wouldn't stream, and the Internet would become a dark forest with no map. DNS is the map to the internet and hosted by an ecosystem of servers, registrars, and domains. In part one of this blog, we'll discuss the servers that keep the internet glued together and some of the records they contain.
Let’s think of mail traveling through the Post Office. The postal worker doesn’t pick up your mail and drive it directly to its destination. A series of local post offices, regional sorting centers, and long-haul transport are responsible in moving your letter or package across the country or world. Each of these stops in its journey; local post offices, sorting centers, and shipping has a specific charter and focus. In the world of DNS a similar structure and charter exists. Root servers would be your long-haul mail transport, airmail, or mail traveling outside of your region. They connect different regions or in this case different domains. Name servers are your regional postal processing facility, sorting, and re-routing mail in the right direction. Authoritative Name Servers are your local post office, providing access to your zip code or in this case your domain. They have the details on delivering to your personal address.
Who is in the forest?
The Root - While there are only 13 Public IP addresses, there are hundreds of Root servers. Who is in control of these? NTIA (National Telecommunications and Information Administration) which is part of the US Department of Commerce. ICANN (Internet Corporation for Assigned Names and Numbers) operates or delegates the operation of these servers to various organizations. These Root servers are the backbone; they do not have specifics for Google or Microsoft, yet they're the authority for who does have the specifics for google.com, microsoft.com, and obc.tech. They point the way to the Name servers who do have the specifics.
Name Servers - Want to send an email, browse a website, or stream a service? You'll need to know how to find them in the forest, and the Name servers have the specifics. There are two different kinds of nameservers, TLD (Top Level Domain) and Authoritative. TLD servers maintain domain extensions such as .com, .net, .gov, .us, etc. Authoritative Servers are the ones holding the details for a domain and provide the IP address to get there, similar to GPS coordinates that pinpoint your destination.
There are other servers in the forest too. Recursive or caching DNS servers are frequently used by ISPs (Internet Service Providers) to cache requested lookups to reduce internet traffic and improve speed. These are the servers you use with your residential broadband service; they keep your devices connected to the map. Another is a Local DNS server which would be specific to your organization. If you use Microsoft Active Directory, you're using this type of server while at work. DNS has shown to be such a critical tool, it's considered a core component to Active Directory functionality.
Email traveling between Domains (e.g. obc.tech and google.com) would first need queries to Root servers to uncover the name server of the recipients’ domain. That name server is then queried to detect the mail servers that receive emails for the domains, before the email is ever sent. Same for browsing to Google.com; that process would be followed to ensure we arrived at the official Google.com website.
What information does DNS hold?
It's basic, yet simple things that stand the test of time. DNS records are no exception to this statement.
"A" records – The most common DNS record. In the Post Office analogy, this is your name being registered with a street address, yet in the DNS world an IP address (street address) is registered with name, such as www.obc.tech.
Alias or CNAME – Another commonly used DNS record; It is used to link a sub-domain or record to an existing record. Let's suppose mail.obc.tech and www.obc.tech are hosted on the same server. Alias/CNAME allows you to link a single record to multiple names.
MX records – Mail Exchange are records that specify which servers receive incoming email.
NS records – Authoritative Name Servers for the domain.
There are several other DNS records that delve more into security, validation, and integration with applications. With DNS being so important and critical to the Internet, security must be important too, right? It certainly is, and it will be the focus of our next article. Stay tuned!