DNS and DHCP

The Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP) are two fundamental utility protocols that operate at the Application Layer to make networks easier to use and manage. DNS is often called the internet's phonebook. Humans prefer to remember names like 'google.com', but network routers work with numerical IP addresses. DNS is the hierarchical and decentralized naming system that translates domain names into IP addresses. When you type a URL into your browser, your computer sends a DNS query to a DNS resolver (usually provided by your ISP). This resolver then queries a series of authoritative DNS servers, starting from the root servers, to find the correct IP address for that domain. The result is then cached on your computer and the resolver to speed up future requests. DHCP is responsible for automating the configuration of devices on a network. Without DHCP, a network administrator would have to manually assign an IP address, subnet mask, default gateway, and DNS server address to every single device. This is tedious and prone to errors. With DHCP, when a device connects to a network, it broadcasts a DHCP Discover message. A DHCP server on the network responds with a DHCP Offer, proposing an IP address and other configuration details. The client then sends a DHCP Request to accept the offer, and the server finalizes the lease with a DHCP Acknowledgment. This process, often called DORA (Discover, Offer, Request, Acknowledge), makes network administration vastly simpler and more scalable.