Computer Networks Fundamentals

Learn how a computer network interconnects devices to exchange data and share resources. Explore types such as Internet of Things, wireless and mobile networks, software-defined networking, cloud, and air-gapped networks.

Define the internet as a global communication infrastructure, not just the web, and describe common internet applications like email, web surfing, social networks, instant messaging, VoIP, video streaming, and peer-to-peer.

Define and compare key protocols such as TCP, HTTP/HTTPS, SMTP, POP, FTP/SFTP, Telnet and SSH, and see how they govern data transmission between devices.

Discover the OSI model, open systems interconnection, with seven layers from physical to application, including HTTP, IP, and Ethernet, and learn layer roles and data naming.

Explore a practical OSI layer walkthrough from application to physical, including UDP vs TCP choices, IP and MAC addressing, and router-driven routing, demonstrated with a Cisco Packet Tracer ping.

Compare the OSI model with the DOD and TCP/IP models, noting OSI's seven layers, DOD's four-layer structure with merged layers, and TCP/IP's four-section stack the course will follow.

Trace the history of computer networks from ARPANET in 1969 to the Internet, through TCP/IP, Cyclades inter-networking, and the 1990s web era with email, web browsing, and e-commerce.

Examine the application layer in the OSI model, its role as an abstraction that enables app-to-app communication, and key protocols like http, ftp, email, telnet, sip, and rtp.

Compare client-server and peer-to-peer architectures, detailing how servers and clients operate, fixed IP addresses, and direct peer communication, with examples like the web, FTP, email, BitTorrent, Skype, and IPTV.

Understand how http enables client-server web object exchanges via requests and responses, using urls and status codes, with caching and persistent connections.

The https protocol secures web communication by encrypting traffic and authenticating servers, building on http with tls replacing ssl. Browsers verify certificates from trusted authorities during connections.

Explain ftp's two tcp connections: a control channel on port 21 and a data channel on port 20, handling user, password, list, retr, and stor commands.

Explore how email works by detailing SMTP's client-server transfer, and compare POP3, IMAP, and web mail protocols for accessing messages on remote servers.

Discover how the domain name system translates domain names to IP addresses using A records and DNS queries, with nslookup and ipconfig practices illustrating local caches and TTL.

Explore remote access fundamentals, comparing Telnet and SSH as client-server protocols, noting Telnet's clear-text credentials on port 23 versus SSH's encrypted authentication on port 22.

Enable logical communication between applications across distant hosts. Choose UDP for unreliable connectionless service and TCP for reliable, connection-oriented delivery.

Explore UDP, a minimal, connection-less transport protocol (RFC 768) that adds four fields and passes data to IP without handshakes, ideal for streaming, VoIP, routing, and real-time gaming.

Explore how the UDP checksum detects errors by summing 16-bit words, handling overflow with wraparound, and using a complement so the receiver's sum should be all ones.

Explore how tcp provides reliable, connection-oriented data transfer atop an unreliable network, detailing the three-way handshake, sequence numbers, acknowledgements, retransmission, and congestion control with slow start and MSS.

Examine the TCP header: ports, checksum, and 32‑bit sequence and acknowledgment numbers for reliable transfer, 16‑bit window for flow control, optional options for MSS and window scaling, and flag bits.

Explore how the network layer handles IP addresses and routing. See how routers use routing tables to determine the path between networks.

Understand how IP addresses identify devices on the network layer, distinguish between logical IP addresses and physical MAC addresses, and interpret the 32-bit binary four-octet format.

See how IP addresses split into the network part and the host part. Learn subnet masks, such as /24 and /16, and how network IDs and broadcast addresses are formed.

Explore the dynamic host configuration protocol (dhcp) for automatic ip address assignment and gateway and dns, using a client–server broadcast exchange (discover, offer, request, ack) on a router or laptop.

Explore ICMP as a network-layer protocol, learn how ping and traceroute diagnose connectivity, and review ICMP’s role in error reporting and DDoS attacks: ping of death, Smurf, and ICMP flood.

Explore how network address translation maps private LAN addresses to a public IP, conserving IPv4 space. See how routers translate and reverse translations for return traffic.

Explore how IPv6 uses 128-bit addresses written in hexadecimal, with eight 16-bit groups separated by colons. Understand address compression with a double colon and leading-zero omission.

Learn routing fundamentals, comparing static and dynamic routing, and see how routing protocols automate path discovery and adapt to congestion in a Cisco Packet Tracer lab.

Identify how autonomous systems use interior gateway protocols (IGP) inside ASes and border gateway protocol (BGP) outside to route traffic across networks.

Explore the link and physical layers, including framing, link access, and multiple access coordination, and examine reliable delivery, error detection, and hardware implementations like NICs.

Explore how a MAC address uniquely identifies network devices, with an organizationally unique identifier and a NIC-specific part, and how to locate it on Windows, Linux, or macOS.

Switch forwards packets within a local network using MAC addresses and builds a MAC address table that learns source addresses to deliver frames without IP routing.

ARP maps IP addresses to MAC addresses at layer two via broadcast requests, populating local ARP caches and enabling routing through gateways for remote hosts.

Explore arp security flaws, how unsolicited arp replies enable spoofing, and how dynamic arp inspection helps detect and block malicious traffic.

Learn how VLAN creates logical sub-networks, using VLAN 10 and VLAN 20 as examples, while trunk links carry multiple VLANs and access links carry a single VLAN.

Ethernet is a link-layer protocol that defines wired frames with a preamble, the SFD, MAC addresses, length, payload, and CRC, and covers 10Base5 and 100BaseT/TX and 1000BaseT standards.

Explore mobility and wireless connectivity by examining wireless links, base stations, coverage, handoff, and network infrastructure, along with common wireless challenges like path loss, interference, multipath, and SNR.

Explore the evolution of Wi-Fi standards from 802.11 to Wi-Fi 6, and learn how Basic Service Set, access points, SSIDs, beacon frames, and scanning enable association in a Wi-Fi jungle.

Discover GSM and GPRS basics, 2G–5G evolution, SMS and MMS, always-on internet, and PoC voice over packets, while examining cellular architecture: BTS, BSC, and MSC with handoff and mobility.

Explore hacking, why hackers attack, and the motivations behind cyber attacks, including data theft, personal vendetta, reputation damage, curiosity, spying, DDoS, and activism by hacktivists.

Identify the top five threats—phishing, malware (viruses, worms, trojan horses), ransomware, DDoS, and SQL injection—then note the OWASP top ten web app risks.

Firewalls inspect and block unsolicited internet traffic, separate trusted and untrusted zones, and protect web apps with web application firewalls that analyze HTTP/HTTPS at the application layer.

Intrusion detection systems mirror network traffic and compare it to signatures to detect suspicious behavior, while intrusion prevention systems block malicious traffic inline or via host-based deployments.