DNS - Domain Name Service

The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates domain names with their corresponding IP addresses so that humans can remember names and computers can resolve the numeric addresses needed to locate and address these resources

How it works

1 - User makes a request: A user tries to access a website by typing the domain name (e.g., www.website.com) into their browser.

2 - DNS Resolver query: The browser sends the query to a DNS Resolver, which is a server responsible for finding the IP address corresponding to the requested domain name.

3 - Query to Root DNS Server: The DNS Resolver queries a Root DNS Server. This server functions to direct the query to the appropriate top-level domain (TLD) name server, such as .com, .net, etc.

4 - Query to TLD Server: The Root DNS Server responds with the address of the appropriate TLD DNS server, and the Resolver queries this server to find out which authoritative DNS server manages the specific domain name.

5 - Query to Authoritative DNS Server: The TLD server responds with the address of the authoritative DNS server for the specific domain. The Resolver then queries this server.

6 - Response from Authoritative DNS Server: The authoritative DNS server holds detailed records for the domain, including the IP address record (A record for IPv4 or AAAA for IPv6). It responds to the Resolver with the IP address corresponding to the requested domain.

8 - DNS Resolver receives the IP: The DNS Resolver now has the necessary IP address and sends this information back to the user's browser.

9 - Connection to the web server: With the IP address in hand, the user's browser can now establish a connection with the web server hosting the site.

10 - Website is loaded: Finally, the web server sends the website data back to the user's browser, which loads and displays the site for the user

Types of DNS

Root DNS Servers: At the top of the hierarchy are the root DNS servers. They are responsible for directing queries to the appropriate top-level domain (TLD) servers. There are 13 sets of root servers spread around the world

Top Level Domain (TLD) Servers: These servers manage the top-level domains, such as .com, .net, .edu, and .org. Each TLD has its own server that maintains information about the domains registered under that TLD

Authoritative DNS Servers: These are the servers that contain authorized information about specific domains, such as google.com, amazon.com, stanford.edu, and wikipedia.org. They provide accurate responses to queries about these domains, including IP addresses and other DNS records

DNS Resolver: Maintained by internet service providers such as Claro, Vivo, and Oi. These resolvers process domain name queries from users, translating them into IP addresses.

Root DNS Servers: Overseen by the IANA (Internet Assigned Numbers Authority), a division of ICANN. The root servers direct queries to the appropriate top-level domain (TLD) servers.

TLD Servers: Operated by specific organizations for each TLD, such as Registro.br, which manages the .br TLD for Brazil. These servers maintain information about the domains registered under their respective TLDs.

Authoritative DNS Servers: Maintained by organizations or individuals who own domains. An example is AWS (Amazon Web Services), which offers the Route 53 service as an authoritative DNS server. These servers have the final authority to respond to queries about their respective domains.

DNS Records

DNS Record types - A
Maps a domain name to its corresponding IPv4 address, which is a 32-bit number. Example Usage: If you want www.example.com to point to the server IP address 192.168.1.1, you would set up an A record for www.example.com with that IP address.

DNS Record types - AAAA
Maps a domain name to its corresponding IPv6 address, which is a 128-bit number used to accommodate the vast number of internet devices. Example Usage: If www.example.com needs to point to an IPv6 address like 2001:0db8:85a3:0000:0000:8a2e:0370:7334, you would use an AAAA record.

DNS Record types - CNAME
Maps a domain name to another domain name instead of to an IP address. This is used to alias one name to another. Example Usage: If you want www.example.com to point to example.com, you would set up a CNAME record for www.example.com pointing to example.com. It’s useful for managing subdomains without needing to update IP addresses in multiple places if they change.

DNS Record types - Name server
Indicates which DNS servers are authoritative for a domain (i.e., responsible for its DNS records). This is critical for directing traffic to the right place for domain-specific queries. Example Usage: If your domain example.com is hosted by a DNS provider whose name servers are ns1.dnshost.com and ns2.dnshost.com, your NS records for example.com would point to these names.

🟠 AWS - Route 53

Amazon Route 53 is a highly scalable and managed Domain Name System (DNS) service provided by Amazon Web Services (AWS).