Research Paper on How DNS Works

Introduction

The Domain Name System (DNS) is a distributed directory whole role is to resolve human-readable hostnames into IP addresses that can be read by a machine. For example, the DNS can translate www.jhs.com to 70.65.76.127. The DNS is also a directory that contains crucial information regarding domain names including email servers, sending verification and SSH fingerprints. Some of the intelligent DNS services that can manipulate responses, therefore deciding which IP or IPs are returned so as to maximize reliability and performance for the clients.

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The DNS could be referred to as the phonebook of the internet. As a result, if the user knows the name of a person but cannot remember their phone number, the user can just look up the name of the person in the phone book. The DNS system provides this traditional service in the age of the internet. For instance, when the user visits https://hgd.com in any browser, the computer uses the DNS at retrieves the IP address of the website of 70.65.76.127. If the DNS was not available, the user would only be able to visit a website by directly visiting its IP address such as https://70.65.76.127.

So how does the DNS work? When a computer user visits a domain, the computer follows a series of steps of turning the web address that is human-readable to an IP address that is machine-readable. This process is repeated every time the user uses a new domain name whether the person is sending an email, visiting websites or listening to an online radio station.

Step 1: information request- this first step starts when the user asks a computer to resolve a hostname. The first location that the computer will look for the IP address that corresponds to the requested hostname is in its local DNS cache. This local DNS usually stores data and information that the computer has retrieved recently. If it does not find the IP locally, it performs a DNS query.

Step 2: Asking the recursive DNS servers- when information is not locally stored, the computer contacts the recursive DNS servers from the ISP. These external computers do the query on behalf of the user. With their own caches and a multitude of ISP users using the same servers, popular domains are likely to be cached already. If found in the server's cache, the process ends there and the user gets his information. Such servers include Google Public DNS.

Step 3: asking the root name servers- if the recursive servers do not have the information that the user is looking for, the query is forwarded to root name servers. This is a computer tasked with answering questions about names of domains. They can be viewed as telephone switchboards for DNS. Essentially, the root name servers have no answers but they can direct the user's DNS queries to another machine that knows about the domain name.

Step 4: asking the TLD name servers-TLD stands for top-level domain. At this point, the root name resolvers look at the first part of the user's request by reading from right to left and direct the query to TLD. Each TLD such as those of .us, .org, .net, .com has its own set of name servers acting like the TLD's receptionist. They refer the user directly to servers containing the information requested. It has to be understood that the TLD resolvers do not have the information that the user requests but their task is to refer the user to the resolvers that contain the information.

Step 5: asking the authoritative DNS resolvers- once the TLD servers have reviewed the next part of the query such as www.example.net, they direct the request to the name servers with this specific domain. The authoritative name resolvers are then tasked with knowing all the information about a specific domain stored in the DNS records. For instance, the user wants to know the IP address for www.exampl.net, so the user will ask the authoritative DNS servers for the address record. Some of the intelligent authoritative name servers have the capability of analyzing an incoming DNS request and giving out a response that is performant for the user that came up with the request to work with.

Step 6: retrieving the record- here, recursive resolvers retrieves the address record for example.net from the authoritative servers and then stores this record in its cache. If another user were to request the record for example.net, the server would not need to go over the process of looking up the record again. All the records have a sort of an expiration date and after this time lapses, the recursive server has to ask for a new copy of the record in order to ensure that the provided information is up to date.

Step 7: receiving the answer- now with the answer, the recursive server returns the address record back to the user's computer where the user's computer stores it in its local cache where it can be reading the IP address from that record. The IP address is then passed to the browser. It is the work of the browser to make a connection with the web server and receive that website. This whole process takes only a fraction of a second to complete.