The Internet is a vast network connecting millions of devices worldwide, allowing them to communicate and exchange data. To ensure seamless connectivity and efficient routing, the Internet utilizes an addressing hierarchy.


In the digital realm, an addressing hierarchy serves as a systematic structure to identify and locate devices connected to the Internet. It enables efficient data transmission by organizing devices into logical groups based on their network and location. This hierarchical approach allows routers to quickly and accurately route data packets to their intended destinations.

IP Addresses

At the core of the addressing hierarchy are IP addresses, which uniquely identify devices on the Internet. An IP address is a numerical label assigned to each device connected to a network. It consists of a series of four sets of numbers, separated by periods.

In the early days of the Internet, IPv4 (Internet Protocol version 4) addresses were primarily used. However, with the growth of the Internet and the exhaustion of available IPv4 addresses, the transition to IPv6 (Internet Protocol version 6) has become necessary. IPv6 offers a significantly larger address space, ensuring the continued growth of the Internet.

Hierarchical Addressing

To efficiently manage the allocation of IP addresses, hierarchical addressing is employed. IP addresses are divided into two parts: the network portion and the host portion. The network portion identifies the network to which a device belongs, while the host portion specifies the unique device within that network.

To further enhance network organization and optimization, subnetting is used. Subnetting involves dividing a large network into smaller subnetworks, each with its own unique network address. Subnet masks are used to determine which portion of the IP address represents the network and which represents the host.

Internet Service Providers (ISPs)

Internet Service Providers (ISPs) play a crucial role in the addressing hierarchy. ISPs are responsible for providing Internet connectivity to end-users. They allocate IP addresses to their customers, ensuring that each device connected to their network has a unique address.

ISPs receive blocks of IP addresses from higher-level entities in the addressing hierarchy, such as Regional Internet Registries (RIRs). This hierarchical allocation ensures efficient management and conservation of IP addresses.

Autonomous Systems (AS)

Autonomous Systems (AS) are networks operated by a single organization or entity. They are an integral part of the Internet’s addressing hierarchy. ASs are assigned unique numbers called Autonomous System Numbers (ASNs), which are used in routing protocols to direct traffic between networks.

ASs provide a way to organize and manage networks efficiently. They facilitate the exchange of routing information among routers and ensure that data packets reach their intended destinations.

Regional Internet Registries (RIRs)

Regional Internet Registries (RIRs) are responsible for managing and distributing IP addresses within specific geographical regions. They receive IP address blocks from the Internet Assigned Numbers Authority (IANA) and allocate them to ISPs and other organizations within their respective regions.

The RIRs operate on a cooperative model and collaborate with ISPs to ensure fair distribution and efficient utilization of IP addresses. They also establish policies and guidelines for IP address allocation and manage the WHOIS database, which contains information about IP address assignments.

Internet Assigned Numbers Authority (IANA)

The Internet Assigned Numbers Authority (IANA) is a global organization responsible for coordinating various Internet-related resources. It oversees the allocation and management of IP addresses, protocol assignments, and domain name system management.

IANA works closely with RIRs to ensure the smooth functioning of the addressing hierarchy. It allocates large blocks of IP addresses to RIRs, which are then distributed to ISPs and other organizations. IANA also manages the global pool of unallocated IP addresses and ensures equitable distribution among the RIRs.

Domain Name System (DNS)

While IP addresses serve as the fundamental building blocks of the Internet’s addressing hierarchy, the Domain Name System (DNS) provides a human-readable naming system. DNS translates domain names (e.g., into IP addresses, enabling users to access websites and other online resources using memorable names.

By linking domain names to IP addresses, the DNS eliminates the need for users to remember complex strings of numbers and allows for flexible resource allocation within the addressing hierarchy.

Classless Inter-Domain Routing (CIDR)

Classless Inter-Domain Routing (CIDR) is an addressing technique that enhances the efficient utilization of IP addresses. It allows for more flexible allocation of address space by eliminating the rigid class-based system used in older IP addressing schemes.

CIDR uses a notation that combines the network address and the number of significant bits in the network portion. This enables efficient allocation of IP addresses, reducing address wastage and supporting the growth of the Internet.

Network Address Translation (NAT)

Network Address Translation (NAT) is a technology used to conserve IP addresses. It allows multiple devices within a private network to share a single public IP address when connecting to the Internet. NAT translates private IP addresses to a single public IP address, enabling devices to communicate with servers and other devices on the Internet.

NAT is widely used in home networks and small businesses to overcome the limitations of available public IP addresses. It helps extend the lifespan of IPv4 addresses and promotes efficient utilization of the existing address space.



Give an introduction to the Internet and its history. Specify the distinction between Internet, Intranet and Extranet. What are the various modes of connecting to the Internet?


Answer the following questions in brief :
(a) What is the role of ISPs in the Internet?
(b) Describe the addressing Hierarchy used in the Internet.
(c) Explain the purpose of DNS in the Internet.


(a) What is the role of HTTP and Web Browsers in the World Wide Web? Name some common Web Browsers in use nowadays and give details of any two.
(b) Explain in detail how searching is carried out in WWW using search engines.


Give a brief description of the following :
(a) Telnet and FTP.
(b) HTML.
(c) TCP/IP


(a) What are the various components of E-mail architecture? Describe the protocols used in E-mail. What is MIME? List the headers defined by MIME.
(b) What is the advantage of using mailing lists? How does the newsgroup service differ from the mailing list facility?


(a) What is the basic structure of HTML documents? List some important tags used in HTML along with heir purpose.
(b) Provide a brief introduction of XML, DHTML, and JavaScript along with the purpose for which they are used.


What are Web Servers? Describe the accessing and using of any one server of your choice.


(a) Describe the various encryption schemes than can be used to secure data.
(b) What is the purpose of Digital Signatures and Firewalls in Internet security?

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