Data Communication & Networks

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About this app

Data Communication & Networks is a clear course in data communication and computer networking for students: 70 topics in 15 sections, from bits and signals to OSI, TCP/IP, IP subnetting and network security.
Every topic has an original drawing, worked examples with real numbers and practice questions. It all works offline.

What you will learn

• Networking Basics: what data communication is, types of networks (LAN, WAN and the Internet), network topologies, protocols and standards, bandwidth, throughput and delay
• Network Models: layers and encapsulation, the OSI reference model, the TCP/IP model, MAC addresses, IP addresses and ports
• Signals: analog and digital signals, sine waves, spectrum, bandwidth and Fourier, bit rate, decibels, transmission impairments, channel capacity with Nyquist and Shannon
• Digital Transmission: line coding, NRZ and RZ, Manchester and differential Manchester, bipolar and multilevel codes, block coding and scrambling, sampling, PCM and quantisation
• Modulation: ASK, FSK and PSK, QPSK and QAM with constellation diagrams, AM, FM and PM
• Multiplexing and Spreading: FDM, time-division multiplexing with T1 and E1, WDM and OFDM, spread spectrum
• Media and Switching: twisted-pair cable, coaxial cable, optical fibre, wireless transmission, circuit and packet switching
• Error Detection and Correction: Hamming distance, parity checks, cyclic redundancy check (CRC), the Internet checksum, Hamming code
• Data Link Control: framing, flow control and stop-and-wait, sliding window protocols (Go-Back-N and Selective Repeat), HDLC and PPP
• Media Access Control: ALOHA, CSMA/CD, CSMA/CA, controlled access and channelisation (TDMA, CDMA)
• Ethernet and Wi-Fi: Ethernet frames and MAC addresses, Ethernet standards and speeds, switches and VLANs, Wi-Fi (IEEE 802.11) up to Wi-Fi 7
• Network Layer: IPv4 addresses, subnetting, VLSM and route summarisation, the IPv4 packet and ICMP, ARP, DHCP and NAT, IPv6 basics, longest prefix match, routing algorithms and protocols
• Transport and Applications: ports and UDP, TCP connections, TCP flow and congestion control, DNS, HTTP and the web, email
• Network Security: security goals and threats, cryptography basics, TLS, VPNs and firewalls
• Quick Reference: a formula sheet with the main data communication formulas on one page

Features
• 70 topics in 15 sections, written for a first course in computer networks
• 70 original drawings: waveforms, line codes, constellations, OSI and TCP/IP layer diagrams, frame formats, timing diagrams and network graphs
• 72 worked examples, from Shannon capacity to CRC division and subnetting step by step
• 168 practice questions with tap-to-reveal answers
• Search all topics from the home screen
• Previous and Next buttons to work through a section in order
• Dark mode
• Works offline, no account needed
• Available in 8 languages: English, Español, Português, Français, Deutsch, العربية, हिन्दी and Bahasa Indonesia

Who it is for
• Students in a data communication and networking course in computer science, IT, electronics or telecommunication engineering
• Anyone learning computer networking from the ground up, from the OSI model to TCP/IP
• Students who want subnetting, CRC and channel capacity worked out step by step before an exam
• Teachers and tutors who want clear drawings of networking concepts

Data Communication & Networks is an independent study aid. Content is checked against IETF RFCs, IEEE 802 and ITU-T standards and MIT OpenCourseWare course notes. It is not affiliated with any textbook publisher, university or standards body.
Data communication and computer networks course: OSI, TCP/IP, subnetting
Updated on
Oct 13, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • This app may share these data types with third parties
    Location, App activity and 2 others
  • No data collected
    Learn more about how developers declare collection
  • Data is encrypted in transit
  • Data can’t be deleted

What’s new

Improved Arabic display: maths, codes and English names in tables now read in the right order.