Why does the browser perform a DNS lookup before making an HTTP request?

Why does the browser perform a DNS lookup before making an HTTP request?

• A. To verify user credentials.
• B. To resolve the domain name in the URL to an IP address needed to establish a connection.
• C. To determine the user's approximate location.
• D. To fetch the SSL certificate.

Answer: (B)

The browser needs an IP address to reach the server. The domain name in a URL is human-friendly, but networks communicate using IP addresses. DNS is the system that translates that domain name into the corresponding IP address. Once the browser has the IP, it can open a connection to that address (on the right port) and then send the HTTP request. Things to note: verification of credentials isn’t handled by DNS, and the goal isn’t to determine your location. SSL certificates are obtained during the TLS handshake after the connection is made, not during DNS resolution. So DNS lookup happens first because you must know where to send the request.

The browser needs an IP address to reach the server. The domain name in a URL is human-friendly, but networks communicate using IP addresses. DNS is the system that translates that domain name into the corresponding IP address. Once the browser has the IP, it can open a connection to that address (on the right port) and then send the HTTP request.

Things to note: verification of credentials isn’t handled by DNS, and the goal isn’t to determine your location. SSL certificates are obtained during the TLS handshake after the connection is made, not during DNS resolution. So DNS lookup happens first because you must know where to send the request.