IPV4
Internet Protocol version 4 is the fourth version of the Internet Protocol. It is used to identify devices on a network and route traffic across the internet. It uses a 32-bit address format, allowing for about 4.3 billion unique IP addresses. An IPv4 address is typically written in four octets, separated by periods. Examples are 192.168.1.1, 10.1.1.1 etc.. IPv4 is widely used for internet communication.
IPv4 IP address Classes
There are five classes in IPv4 : A, B, C, D and E.
Each class has a specific range of IP addresses (Each Ranges have its own number of devices and number of networks).
Class A, B, and C are used by the majority of devices on the Internet.
Class D and class E are for special uses.
IP addresses are categorized into private and public ranges
Public IP Address Range:
Public IP addresses are used on the internet and can be routed globally.
Private IP Address Ranges
These are reserved for use in private networks and are not routable over the public internet.
Class A (Supports 16 million hosts per network)
- IP Range: 1.0.0.0 to 127.255.255.255
- Subnet Mask: 255.0.0.0 (or /8)
- Default Network Size: 8 bits for the network portion, 24 bits for the host portion
- Usage: Primarily used for large networks.
- Private Range: 10.0.0.0 to 10.255.255.255
- Hosts per Network: 16,777,214
Class B (Supports 65,534 hosts per network)
- IP Range: 128.0.0.0 to 191.255.255.255
- Subnet Mask: 255.255.0.0 (or /16)
- Default Network Size: 16 bits for the network portion, 16 bits for the host portion
- Usage: Medium to large networks.
- Private Range: 172.16.0.0 to 172.31.255.255
- Hosts per Network:65,534
Class C (Supports 254 hosts per network)
- IP Range: 192.0.0.0 to 223.255.255.255
- Subnet Mask: 255.255.255.0 (or /24)
- Default Network Size: 24 bits for the network portion, 8 bits for the host portion
- Usage: Typically used for small networks, such as home and small office networks.
- Private Range: 192.168.0.0 to 192.168.255.255
- Hosts per Network:254
Class D (Multicast Addresses)
- IP Range: 224.0.0.0 to 239.255.255.255
- Usage: Used for multicast communications (group communication, like streaming, or broadcast applications).
- Default Subnet Mask : Reserved
- Hosts per Network : Multicast Addresses
Class E (Experimental Addresses)
- IP Range: 240.0.0.0 to 255.255.255.255
- Usage: Reserved for experimental or research purposes and not used in general networking.
- Default Subnet Mask : Reserved
- Hosts per Network :Experimental and Research
Subnetting
A subnet (short for "subnetwork") is a logical division of an IP network into smaller, more manageable segments. Subnetting allows network administrators to organize a larger network into smaller, efficient sub-networks, improving performance and security.
An IPv4 address is 32 bits long, typically written as four octets (e.g., 192.168.1.0).
Subnet Mask Defines which portion of the IP address refers to the network and which part refers to the host within that network. It is also written in dotted decimal format (e.g., 255.255.255.0).
The subnet mask uses 1s to identify the network portion and 0s to identify the host portion.
Example:
- IP Address: 192.168.1.10
- Subnet Mask: 255.255.255.0
- Step-by-Step:
Convert IP Address and Subnet Mask to Binary:
192.168.1.10 = 11000000.10101000.00000001.00001010
255.255.255.0 = 11111111.11111111.11111111.00000000 - Network Address
By performing a bitwise AND operation between the IP address and subnet mask, the network address is 192.168.1.0.
- Subnet Information
This subnet allows for 256 IP addresses (from 192.168.1.0 to 192.168.1.255)
but the first address (192.168.1.0) is reserved for the network
and the last address (192.168.1.255) is reserved for broadcast.
The valid host range is from 192.168.1.1 to 192.168.1.254.
To subnet the IP address 192.168.1.0/27, let's break it down:
Understanding the /27 Prefix:
A /27 subnet mask means that the first 27 bits of the IP address are used for the network part, and the remaining 5 bits are used for hosts. The subnet mask for /27 is:
Copy code
255.255.255.224
This gives us 32 total addresses in each subnet (2^5 = 32). Out of these, 30 addresses can be assigned to hosts (2 addresses are reserved: one for the network address and one for the broadcast address).
- Subnetting the 192.168.1.0/27 Network:
The network address is 192.168.1.0 and the subnet mask is 255.255.255.224.
The first address of the subnet is the Network Address.
The last address of the subnet is the Broadcast Address.
The remaining addresses are available for host assignment.
- Calculating Subnets:
Since the subnet mask is /27, the network is divided into 8 subnets of 32 addresses each. Below is the breakdown of each subnet.
| Subnet Number | Network Address | First Usable IP | Last Usable IP | Broadcast Address | Number of Hosts |
|---|---|---|---|---|---|
| 1 | 192.168.1.0 | 192.168.1.1 | 192.168.1.30 | 192.168.1.31 | 30 |
| 2 | 192.168.1.32 | 192.168.1.33 | 192.168.1.62 | 192.168.1.63 | 30 |
| 3 | 192.168.1.64 | 192.168.1.65 | 192.168.1.94 | 192.168.1.95 | 30 |
| 4 | 192.168.1.96 | 192.168.1.97 | 192.168.1.126 | 192.168.1.127 | 30 |
| 5 | 192.168.1.128 | 192.168.1.129 | 192.168.1.158 | 192.168.1.159 | 30 |
| 6 | 192.168.1.160 | 192.168.1.161 | 192.168.1.190 | 192.168.1.191 | 30 |
| 7 | 192.168.1.192 | 192.168.1.193 | 192.168.1.222 | 192.168.1.223 | 30 |
| 8 | 192.168.1.224 | 192.168.1.225 | 192.168.1.254 | 192.168.1.255 | 30 |
- Subnet Details:
Total Subnets: 8
Hosts per Subnet: 30
Subnet Mask: 255.255.255.224 or /27
Network Size: 32 addresses per subnet (30 usable for hosts)
Usable IP addresses in the subnets can be assign to devices, like computers, printers, or other network devices.
IPv4 has several advantages
Mature and Well-Established: IPv4 has been in use since the 1980s, making it highly reliable, well-supported, and compatible with almost all devices and networks worldwide.
Simple and Lightweight: Its 32-bit address structure is relatively simple, which helps in easy implementation and minimal processing overhead for devices and routers.
Wide Adoption: IPv4 is universally deployed, meaning that virtually all internet services, devices, and networks support it, ensuring global connectivity.
Established Routing Infrastructure: The routing mechanisms and protocols (e.g., OSPF, BGP) in IPv4 are well-understood, efficient, and have been optimized over time.
Extensive Documentation and Tools: Due to its long history, there is an abundance of tools, tutorials, and documentation available for IPv4, making it easier to troubleshoot and manage networks.
IPv4 has several disadvantages
Limited Address Space: IPv4 uses 32-bit addresses, which allows for only about 4.3 billion unique IP addresses. With the growing number of devices, this address space is quickly exhausted.
Address Exhaustion: Due to the limited number of IPv4 addresses, many organizations rely on techniques like NAT (Network Address Translation) to share a single public IP address, which can complicate network management and performance.
Inefficient Routing: IPv4 addresses are not as efficient for routing as they could be, leading to increased overhead in routing tables and slower processing times.
Security Issues: IPv4 was designed without strong built-in security features, and while security protocols like IPsec can be added, they are not universally implemented.
Network Configuration Complexity: IPv4 networks often require manual configuration for tasks like assigning IP addresses, making management more difficult as networks grow.
IPV6
IPv6 (Internet Protocol version 6) is the most recent version of the Internet Protocol (IP), designed to address the limitations of its predecessor, IPv4.
IPv6 uses 128-bit addresses, allowing for a vastly larger address space—around 340 undecillion (3.4×10²⁸) unique IP addresses—compared to the 32-bit address space of IPv4.
This expansion was necessary due to the exhaustion of IPv4 addresses. IPv6 also simplifies network configuration, improves security features (like mandatory IPsec encryption), and supports better routing and network efficiency.
The address format is typically written in eight groups of four hexadecimal digits, separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).
Network Past Paper Questions to try
Consider the following scenario
The PQR Company has three departments, namely Finance, Marketing and Human Resource (HR). At present all the activities of the PQR Company are conducted manually. The company decides to computerise all their activities by establishing an IT unit with a computer lab for staff training. Resources will be allocated for each department and the IT unit as follows.
| Department | Computers | Printer Type | Software Server |
|---|---|---|---|
| Finance | 28 | 01 Network Printer | Accounting Information System (AIS) |
| HR | 40 | 01 Network Printer | Human Resource Information System (HRIS) |
| IT Unit | 50 | 01 Printer | Learning Management System (LMS) |
| Marketing | 35 | 01 Network Printer | Marketing Information System (MKIS) |
The Company Propose the following:
- A Local Area Network (LAN) for each Department and IT unit in order to share specific software and resources.
- LANs in each department to be interconnected via IT Unit..
- All computers to be given efficient Internet connectivity with the help of DNS (Domain Name System) and proxy servers..
- An Iternet Service Provider (ISP) to supply the Internet connectivity to the IT Unit.
- The Entire network to be protected through a firewall.
- Which network topology is the most suitable to satisfy all the above mentioned requirements? Give one reason to justify your answer.
- Which network Administrator has received 192.168.14.0/24 as the IP address block for the company. The IP address for the nodes are to be alocated after making four subnets from this address block for each department/unit.
- Showing clearly the connection topology and the devices, draw the logical arrangement for the company network that the network administrator can implement to fulfill the company's requirements. (Assume that additional IP addresses can be obtained.)
- Network administrator decides to dynamically manage the IP addresses of the entire network. Write down the mechanism that needs to be implemented to achieve this task.
The following incomplete table shows the sub-netting. Write down tha missing IP addresses for each department/unit using the following table format. (Assume that subnetting is done under the consideration of future expansion of each department/unit.)
| Department | Network ID | Broadcast ID | Subnet Mask | Usable IP Address Range |
|---|---|---|---|---|
| Finance | 192.168.14.0 | 192.168.14.63 | 255.255.255.192 | 192.168.14.1 - 192.168.14.62 |
| HR | ||||
| IT Unit | ||||
| Marketing |
Network Past Paper Questions to try
Consider the following scenario:
A school has acquired the following resources to its Admnistrative (Admin), Laboratory (Lab) and Library (Lib) buildings:
| Building | Resources |
|---|---|
| Admin | 5 Computers, 1 printer |
| Lab | 40 Computers, 1 printer |
| Lib | 10 Computers, 1 printer |
A scholl computer network has to be created to fulfil the following requirements:
- Each building needs to have its own local area network (LAN) in order to share the printer.
- The above three networks are to be interconnected so that the School Information System (SIS) which is running on one computer in the Admin building and the Library Iinformation System (LIS) running on one computer in the Lib building are accessible from all computers.
- All computers are to be given efficient internet connectivity as well. For this purpose the school has subscribed to an Internet Service Provider (ISP) who is to supply the Internet connectivity to the Lab building. Tha Lab building is seperated from the other two buildings by approximately 500m. One computer in the Lab building is to be used as the DNS server. Another computer in the Lab building is to be used as the proxy server.
- The entire network is to be protected through a firewall.
- The Principal has received the 192.248.16.0/24 IP address block for the school. The IP addresses for the computers are to be allocated after making three subnets from this address block for three buildings.
Assuming such subnetting is done, write down the relevant network address, subnet mask and the allocated range of IP addresses for each building using the following table format to present your answer.
Building Network Address Subnet Mask IP Address Range Admin Lab Lib - Give one reason as to why a fully connected (all-to-all) network topology is not suitable for this school computer network
- The Lab administrator who is responsible to setup the school computer network has requested for switches and a router.
Showing clearly the network connection topology and the devices, draw the network diagram to represent the logical arrangement for the school computer network that the Lab adminstrator can implement to fulfil the school requirements. - Give one reason as to why TCP is preferred over UDP as the transport protocol for the school computer network.
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