4_Organisation of Computer Networks_methodical_lesson_1_2

Methodological Instructions

Theme: Organization of Computer Networks

Objective:

10.6.1.1 describe the purpose of network components (nodes, routes, commutators);

10.6.1.2 explain the purpose and presentation of an IP address;

10.6.1.3 explain the purpose of DNS;

10.6.1.4 explain the purpose of a private virtual network

Assessment criteria

Explain the purpose of network components (nodes, routes, commutators);

Explain the purpose of DNS;

Key words and phrases:

Network protocols, IP address, Domain Name, Domain Name Server, URL, a network identifier part, a host identifier part.

Useful sets of phrases for dialogue and writing:

Network protocols are  used …

Types of  network protocols are …

Protocol for sending and receiving emails …

Protocol for loading websites …

Protocol for  sending files …

Protocol for  loading secure websites …

The IP address is used …

The Domain Name is used …

The URL is used …

I.                   THEORY

What are IP Addresses?

An IP address is a 32-bit identifier assigned to a host that uses the Internet Protocol. The IP address is represented by four octets (8-bit fields). In decimal form, an IP address consists of four fields separated by dots, where each field contains a value in the range 0 - 255. This is called dotted decimal notation.

Each host ID must be unique within a given network, and each network number must be unique within a given internet. Host IDs are assigned by the network administrator. The network number is assigned by the inter-network administrator. For a public network on the Internet, you must obtain a network number assigned by the Network Information Center (NIC).

An IP address consists of two parts. The first part of the address, called the network number, identifies a network on the internet; the remainder, called the host ID, identifies an individual host on that network. Historically, three classes of IP addresses have been defined:

Class A--Only the first field identifies the network, and the number in the first field must be in the range 1 - 126 (127 is reserved for loopback). Class A networks are very large. Host numbers 0.0.0 and 255.255.255 are reserved, and one octet is reserved for other purposes, so there can be almost 17 million (224-2) hosts in a class A network. The 126 class A network numbers have been allocated.

Example: 26.4.0.1, for host 4.0.1 on net number 26.

Class B--The first two fields identify the network, and the number in the first field must be in the range 128 - 191. Class B networks are large. Host numbers 0.0 and 255.255 are reserved, so there can be up to 65,534 (216-2) hosts in a class B network. Most of the 16,382 class B addresses have been allocated.

Example: 128.89.0.26, for host 0.26 on net 128.89.

Class C--The first three fields identify the network, and the number in the first field must be in the range 192 - 223. (The range 224 - 255 is reserved for classes D and E, for experimental work.) Class C networks are relatively small. Host numbers 0 and 255 are reserved, so there can be up to 254 (28-2) hosts in a class C network. Most LANs are class C networks. There can be over 2 million class C networks in an internet.

Example: 192.15.28.16, for host 16 on net 192.15.28.

Address Masks

An address mask determines which portion of an IP address identifies the network and which portion identifies the host. Like the IP address, the mask is represented by four octets. (An octet is an 8-bit binary number equivalent to a decimal number in the range 0 - 255). If a given bit of the mask is 1, the corresponding bit of the IP address is in the network portion of the address, and if a given bit of the mask is 0, the corresponding bit of the IP address is in the host portion.

The following table shows the mask 255.255.255.0 in both decimal and binary form, aligned with the class C address 192.15.28.16, also in both decimal and binary form

VISUAL AIDS AND MATERIALS.

1.        Slides

2.        https://searchnetworking.techtarget.com/tutorial/Protocols-Lesson-4-Internet-Protocol-classes-Network-and-host-ID

3.        https://www.webopedia.com/TERM/D/domain_name.html

4.        https://www.quora.com/In-IP-addresses-what-is-meant-by-network-ID-and-host-ID

5.         http://www3.safenet-inc.com/esafe/esafe_reporter/Concepts/Understanding_IP_Addresses/01_Understanding_IP_Addresses.htm

6.        Скачано с www.znanio.ru