DNS Lookup process - things involved
Step 1: Requesting Website Information
First, you visit a website by typing a domain name into a web browser. Your computer will start resolving the hostname, such as www.liquidweb.com. Your computer will look for the IP address associated with the domain name in its local DNS cache, which stores DNS information that your computer has recently saved. If it is present locally, then the website will be displayed. If your computer does not have the data stored, then it will perform a DNS query to retrieve the correct information.
Step 2: Contact the Recursive DNS Servers
If the information is not in your computer’s local DNS cache, then it will query the recursive DNS servers from your (ISP) Internet service provider. Recursive DNS servers have their local DNS cache, much like your computer. Given that many of the ISP’s customers are using the same recursive DNS servers, there is a chance that common domain names already in its cache. If the domain is cached, the DNS query will end here and the website displayed to the user.
Step 3: Query the Authoritative DNS Servers
If a recursive DNS server or servers do not have the information stored in its cache memory, the DNS query continues to the authoritative DNS server that has the data for a specific domain. These authoritative name servers are responsible for storing DNS records for their respective domain names.
Step 4: Access the DNS Record
For our example, to find out the IP address for www.liquidweb.com, we will query the authoritative name server for the address record (A record). The Recursive DNS server accesses the A record for www.liquidweb.com from the authoritative name servers and stores the record in its local DNS cache. If other DNS queries request the A record for www.liquidweb.com, the recursive server will have the answer and will not have to repeat the DNS lookup process. All DNS records have a time-to-live value, which shows when a DNS record will expire. After some time has passed, the recursive DNS server will ask for an updated copy of the DNS record.
Step 5: Final DNS Step
The Recursive DNS server has the information and returns the A record to your computer. Your computer will store the DNS record in its local DNS cache, will read the IP address from the DNS record, and pass this information to your browser. The web browser will connect to the web server associated with the A records IP and display the website.
The entire DNS lookup process, from start to finish, takes only milliseconds to complete. For a more profound understanding let’s break down the previously mentioned DNS components that are relevant to the DNS lookup process.
References:
https://www.liquidweb.com/kb/understanding-the-dns-process/
Step 1: Requesting Website Information
First, you visit a website by typing a domain name into a web browser. Your computer will start resolving the hostname, such as www.liquidweb.com. Your computer will look for the IP address associated with the domain name in its local DNS cache, which stores DNS information that your computer has recently saved. If it is present locally, then the website will be displayed. If your computer does not have the data stored, then it will perform a DNS query to retrieve the correct information.
Step 2: Contact the Recursive DNS Servers
If the information is not in your computer’s local DNS cache, then it will query the recursive DNS servers from your (ISP) Internet service provider. Recursive DNS servers have their local DNS cache, much like your computer. Given that many of the ISP’s customers are using the same recursive DNS servers, there is a chance that common domain names already in its cache. If the domain is cached, the DNS query will end here and the website displayed to the user.
Step 3: Query the Authoritative DNS Servers
If a recursive DNS server or servers do not have the information stored in its cache memory, the DNS query continues to the authoritative DNS server that has the data for a specific domain. These authoritative name servers are responsible for storing DNS records for their respective domain names.
Step 4: Access the DNS Record
For our example, to find out the IP address for www.liquidweb.com, we will query the authoritative name server for the address record (A record). The Recursive DNS server accesses the A record for www.liquidweb.com from the authoritative name servers and stores the record in its local DNS cache. If other DNS queries request the A record for www.liquidweb.com, the recursive server will have the answer and will not have to repeat the DNS lookup process. All DNS records have a time-to-live value, which shows when a DNS record will expire. After some time has passed, the recursive DNS server will ask for an updated copy of the DNS record.
Step 5: Final DNS Step
The Recursive DNS server has the information and returns the A record to your computer. Your computer will store the DNS record in its local DNS cache, will read the IP address from the DNS record, and pass this information to your browser. The web browser will connect to the web server associated with the A records IP and display the website.
The entire DNS lookup process, from start to finish, takes only milliseconds to complete. For a more profound understanding let’s break down the previously mentioned DNS components that are relevant to the DNS lookup process.
References:
https://www.liquidweb.com/kb/understanding-the-dns-process/
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