Unit 1 - Introduction - IT
- 1. Introduction Unit 1 By Deep Raj Bhujel
- 2. • Internet: Compare with WWW • Intranet: • Internet Number: Internet Protocol address (IP address) Autonomous System (AS) number (ASN)
- 3. Internet Assigned Numbers Authority (IANA) • IANA is the entity that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet Protocol-related symbols and numbers. • IANA is a department operated by the Internet Corporation for Assigned Names and Numbers, also known as ICANN (Internet Corporation for Assigned Names and Numbers).
- 4. Request for Comments (RFC) • IANA is broadly responsible for the allocation of globally unique names and numbers that are used in Internet protocols that are published as RFC documents. • RFC is a memorandum published by the Internet Engineering Task Force (IETF) describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.
- 5. Internet Registry (IR): • Regional Internet registry (RIR) • National Internet Registry (NIR) • Local Internet registry (LIR) e.g. ISP
- 6. Internet service provider (ISP) • Access providers ISPs: • Hosting ISPs: • Transit ISPs: • Virtual ISPs: • Free ISPs:
- 7. Internet Domain: • A domain name is an identification string that defines a realm of administrative autonomy, authority, or control on the Internet. Domain names are formed by the rules and procedures of the Domain Name System (DNS). • In general, a domain name represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet.
- 8. • top-level domains (TLDs): generic top-level domains (gTLDs) country code top-level domains (ccTLDs) • Structure of domain name: • Subdomain:
- 9. Reserved Domain Names: • example: reserved for use in examples • invalid: reserved for use in obviously invalid domain names • localhost: reserved to avoid conflict with the traditional use of localhost as a hostname • test: reserved for use in tests
- 10. Domain Name System (DNS): • address (A) records, • Canonical name (CNAME) records, • name server (NS) records, • mail exchanger (MX) records, • Pointer (PTR) records
- 11. • Client Lookup: • Reverse Lookup: • Domain Name Registrar:
- 12. Internet Backbone Networks: • Optical backbone: • Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. • The process of communicating using fiber-optics involves the following basic steps: creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal.
- 13. Optical Fiber: • Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications. • An optical fiber is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or “light pipe”. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. • Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that only support a single mode are called single-mode fibers (SMF).
- 14. Marine Cables: • A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean. • Modern cables are typically 69 millimetres (2.7 in) in diameter and weigh around 10 kilograms per metre (7 lb/ft), although thinner and lighter cables are used for deep-water sections. • Also, the total carrying capacity of submarine cables is in the terabits per second, while satellites typically offer only megabits per second and display higher latency.
- 15. 1. Polyethylene 2. "Mylar" tape 3. Stranded metal (steel) wires 4. Aluminum water barrier 5. Polycarbonate 6. Copper or aluminum tube 7. Petroleum jelly 8. Optical fibers
- 16. Teleports: • Teleports are the ground-based side of the global satellite network – gateways that provide terrestrial networks with access to orbiting satellite transponders. • But they are more than simple gateways. • Teleports bridge incompatible systems and protocols, host and distribute content, and act as the hubs of broadband B2B networks.
- 17. Satellite Links: • A satellite link is a communications subsystem that involves a link between a transmitting Earth station and a receiving Earth station via a communications satellite. The Satellite: The Ground Station:
- 18. Communications satellites Advantages • Flexibility: • Mobility: • Speedy deployment: • Coverage over the globe: Disadvantages • Cost: • Propagation delay: • Specialised satellite terminals required: Q. GEO VS LEO
- 19. Terrestrial Link: • A communications line that travels on, near or below ground is terrestrial link.