When you type a domain name such as google.com into a web browser, how does the browser ultimately find the correct IP address to connect to?

Introduction / Context:
Humans prefer to use readable names such as google.com, while computers communicate using numerical IP addresses. The Internet needs a mechanism to translate between these two forms. Understanding how a browser converts a domain name into an IP address is fundamental to networking and web technology. This question asks you to identify the correct mechanism used in this translation.

Given Data / Assumptions:

• The user enters a domain name such as google.com into the browser address bar.
• The browser needs an IP address to open a TCP connection to the web server.
• The operating system and network configuration provide access to DNS servers.
• We are considering standard Internet behaviour, not special offline caches or hard coded mappings beyond hosts files and DNS.

Concept / Approach:
The key system used to map domain names to IP addresses is the Domain Name System, commonly called DNS. DNS is a distributed, hierarchical naming system. When a browser needs the IP address for a domain, it first checks local caches and then sends a DNS query through the operating system to configured DNS resolvers, often provided by the Internet service provider or a public DNS service. Those resolvers contact authoritative DNS servers as necessary and return the correct IP address to the client. The browser then uses that IP address to establish a network connection to the server.

Step-by-Step Solution:
Step 1: The user types a domain name into the browser and presses Enter.Step 2: The browser asks the operating system for the IP address associated with that domain.Step 3: The operating system checks local caches and, if necessary, sends a DNS query to the configured DNS resolver.Step 4: The DNS resolver follows the DNS hierarchy, contacting root, top level domain, and authoritative servers to find the IP address.Step 5: The resolver returns the IP address to the operating system, which passes it to the browser so that the browser can open a connection.

Verification / Alternative check:
You can verify this process by using tools such as nslookup or dig from a command line. When you run nslookup google.com, the tool shows which DNS servers are being queried and what IP addresses are returned. Network diagnostic tools and browser developer consoles also reveal that DNS lookup happens before a connection is made. These observations confirm that DNS, not random guessing or broadcasting, is responsible for name resolution.

Why Other Options Are Wrong:
Option B is incorrect because broadcasting a query to every computer on the Internet would be extremely inefficient and is not how the Internet is designed. Option C is wrong because randomly guessing IP addresses would almost never find the correct server quickly and would look like hostile scanning. Option D is incorrect because there is no practical way to store a complete global list of all domains and IP addresses inside each browser; that information changes constantly and is managed by DNS infrastructure instead.

Common Pitfalls:
People sometimes think that browsers have hard coded addresses for popular sites, but in general DNS is used even for well known domains. Another pitfall is to underestimate the caching that happens at many levels, including the browser, operating system, router, and DNS servers. Caching reduces lookup time but does not change the basic mechanism. Understanding this process helps with debugging network problems and configuring custom DNS services.

Final Answer:
The browser relies on the Domain Name System, querying DNS servers to resolve the domain name into an IP address, which is option A.