This book is designed for the course on Data Communication and Computer Networks offered to students taking the DOEACC's 'A' level certificate examination. The book will also be useful to the Diploma students who take a paper on Data Communications and Networks. Key Features: Comprehensive coverage of Communications and Transmission fundamentals. Data Link Layer covered in detail as two separate chapters. Detailed discussion on the Network Layer. The last 5 Question papers of DOEACC 'A' level examinations included at the end of the book as an appendix. Comprehensive coverage of Communications and Transmission fundamentals. Data Link Layer covered in detail. DOEACC 'A' level examination question papers included as an appendix. Table of Content: Chapter 1 An Introduction to Communications Chapter 2 Data Transmission Chapter 3 Modulation Chapter 4 Transmission Media Chapter 5 Fiber Optic Communication Chapter 6 Wireless Transmission Chapter 7 Multiplexing Chapter 8 Switching Chapter 9 Telecommunication Networks Chapter 10 Introduction to Computer Networks Chapter 11 ISO-OSI Reference Model Chapter 12 TCP/IP Protocol Suite Chapter 13 Modems Chapter 14 Elementary Protocols for Channel Allocation Chapter 15 IEE Standard 802 for LANs and MANs Chapter 16 Multichannel Data Communication Chapter 17 Data Link Layer-I Chapter 18 Data Link Layer-II Chapter 19 X.25 Network Chapter 20 Loca