The Internet is a global network of networks comprising millions of independent networks that interconnect and exchange data by adhering to shared protocols.

The Internet

A Media Access Control (MAC) address is a permanent hardware identifier embedded directly into a device's network interface card. It operates at the local link level to uniquely distinguish and identify a device on a local network segment.

MAC Address

An Internet Protocol (IP) address is a logical network-layer identifier assigned to a device to enable addressing and the routing of packets across multiple interconnected networks. Rather than identifying a permanent physical hardware interface or pinpointing an individual's exact physical location, an IP address typically specifies a device's network or regional presence.

IP Address

The Domain Name System (DNS) functions as the directory or "phone book" of the Internet by translating human-readable names (such as example.com) into numeric IP addresses that networking equipment requires to route packets. When a user navigates to a domain, the device initiates a DNS lookup to request the corresponding IP address from a DNS server; without DNS resolution, users would be required to memorize and manually input numeric IP addresses for every website.

Domain Name System (DNS)

Transmission Control Protocol (TCP) is a core transport-layer protocol that provides reliable, ordered data delivery between programs running on networked hosts. Operating directly on top of the Internet Protocol (IP), TCP numbers each unit of data, confirms receipts through acknowledgments, resends lost packets, and regulates transmission speed to avoid congestion. TCP requires a connection to be established via a handshake before data is transmitted, making it ideal when every byte must arrive accurately, such as for web pages, email, and file transfers.

Transmission Control Protocol (TCP)

The TCP three-way handshake is an ordered connection-establishment procedure that client and server applications perform before any application data is transmitted:

1. **SYN**: The client transmits a SYN ("synchronize") message to request opening a connection.
2. **SYN-ACK**: The server responds with a SYN-ACK message to acknowledge the request and agree to establish the connection.
3. **ACK**: The client sends a final ACK message, completing connection setup.

Only after this three-way exchange is complete does actual data transfer begin. This setup ensures connection reliability but makes TCP slightly slower to initiate than connectionless protocols like UDP.

TCP Three-Way Handshake

Bandwidth and latency represent two distinct metrics of network performance. Bandwidth measures the data transmission capacity of a connection, specifying how much data can be transferred per second. In contrast, latency measures delay, representing the time it takes for data to travel across the network. A common misconception is that increasing bandwidth always reduces latency; however, a wide connection that experiences high delay will still feel slow and laggy.

Bandwidth vs. Latency

The cloud refers to physical data centers comprising remote computers and servers that are accessed over a network. Contrary to the misconception that the cloud is an abstract virtual entity detached from physical hardware, cloud services run on real, tangible computing hardware owned and operated by third-party providers.

The Cloud

University of Michigan - Ann Arbor

Ch.4 Network Performance Characteristics - Network Architecture and Packet Flow: Inside Modern Communication Systems @ University of Michigan - Ann Arbor

Bandwidth, Latency, and Common Networking Misconceptions - Network Architecture and Packet Flow: Inside Modern Communication Systems @ University of Michigan - Ann Arbor

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