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DMARC

11 August, 2020

How are Domains Mapped to IP Addresses

DNS servers exist not only because we prefer to use human-readable names to access websites but computers need IP addresses to access websites. How does the DNS translate domain name to IP addresses? The process is called DNS resolution and plays out over eight steps.

When you type a domain or full web address into your browser, www.netflix.com for instance, your browser sends a message to the network asking for help. This exchange is commonly known as a query.
Your computer contacts a machine known as a recursive resolver to locate the previously cached IP address, or if it’s a first-time search, the machine 'recursively' searches for it.
If the recursive resolver fails to find the address, they query the DNS root name servers for the domain IP address.
The root name servers direct your ISP through the DNS hierarchy by referring your ISP recursive resolver to the necessary top-level domain name servers by scanning the top-level domain.
Each top-level domain in the DNS has its own set of nameservers. Once the resolver has requested the IP address from them, they are referred to a more applicable DNS. At this point, the DNS servers are reviewing the second-level domain.
Your ISP queries the referred DNS name servers for the applicable IP address. Each domain has an assigned set of DNS name servers responsible for holding the IP address and all over information relating to the domain.
Your ISP provider’s resolver retrieves the domains A record for Netflix.com from the authoritative name servers and stores it in its cache in case of future queries by anyone else.
The last step sees your ISP’s recursive servers deliver the A record to your computer. Your computer now reads the record-holding all the information about the domain and forwards the IP address to your browser. Your browser will then open a connection to www.Netflix.com so you can binge-watch your favorite sitcom from the 90s. This entire eight-step process is complete within a few tenths of a second however different DNS servers behave differently regarding speed and security.