An IP Address is a unique numerical identifier assigned to every device on a network, allowing data to be routed to the correct destination. These addresses are typically dynamic, meaning they are temporarily assigned by a DHCP server when a device connects.
IPv4 uses a 32-bit addressing scheme, represented as four blocks of denary numbers (0-255) separated by dots, providing approximately (4.3 billion) unique addresses. Due to the explosion of connected devices, this pool has become exhausted.
IPv6 was developed to solve address exhaustion by using a 128-bit scheme, represented as eight blocks of four hexadecimal digits separated by colons. This provides addresses, which is a virtually inexhaustible supply for the foreseeable future.
The Domain Name System (DNS) acts as the 'phone book' of the Internet, translating human-readable domain names (like www.example.com) into the numerical IP addresses that computers use to locate servers.
When a URL is entered, the browser first checks its local cache; if the address is unknown, it queries a DNS Resolver, which may then contact Root, TLD (Top-Level Domain), and Authoritative servers in a recursive process.
Once the IP address is found, it is returned to the browser, which then establishes a direct connection to the web server to request the specific site data.
Distinguish Infrastructure from Service: Always clarify that the Internet is the network (hardware/protocols) while the WWW is the content (pages/files). Marks are often lost by using these terms interchangeably.
Address Calculations: Remember that IPv4 uses 4 bytes (32 bits) and IPv6 uses 16 bytes (128 bits). Be prepared to identify valid vs. invalid addresses based on these ranges (e.g., 256 is invalid in IPv4).
DNS Flow: Memorize the sequence of a DNS lookup. If a question asks what happens when a URL is typed, start with the browser cache and end with the rendering of the page by the browser.
Public vs. Private IP: Understand that Private IPs are for internal LAN communication and are not routable on the global Internet, whereas Public IPs must be globally unique.
