A subnet, short for subnetwork, is a smaller and clearly defined section of a larger IP network. Instead of placing every device into one large network, an organisation can divide its address space into multiple smaller groups. Each group has its own IP address range and can be used for a particular office, department, server environment, cloud workload, customer service, or network function.<\/p>\n\n\n\n
A subnet can be compared to a street inside a city. The city represents the entire network, while the street represents one smaller address range. Devices within the same subnet can usually communicate directly through the local network. When traffic needs to reach another subnet, it is normally sent through a router or firewall.<\/p>\n\n\n\n
Subnetting makes networks easier to organise, secure, monitor, and expand. A business might use one subnet for employee computers, another for guest Wi-Fi, another for production servers, and another for network management. Each subnet creates a logical boundary that administrators can use when designing access rules and routing policies.<\/p>\n\n\n\n
The main purpose of subnetting is to divide a large network into manageable sections. A flat network may be acceptable for a small home environment, but it quickly becomes difficult to control when hundreds or thousands of devices are connected.<\/p>\n\n\n\n
For example, a company may separate its staff computers, printers, voice phones, security cameras, servers, and guest devices into different subnets. This allows the network team to apply different rules to each group. Guest devices may be allowed to access the Internet but blocked from internal servers. Database systems may be reachable only by approved application servers. Management interfaces may be limited to a small group of administrators.<\/p>\n\n\n\n
Subnetting can also reduce unnecessary local traffic. Some network communication is intended only for devices within the same local segment. Dividing a large environment into smaller subnets prevents every device from receiving traffic that is not relevant to it.<\/p>\n\n\n\n
Subnetting does not automatically provide security. A router may still allow traffic between two subnets unless a firewall or access-control policy blocks it. The subnet creates the boundary, while security rules determine what is allowed to cross that boundary.<\/p>\n\n\n\n
An IP address contains two important parts: a network portion and a host portion. The network portion identifies the wider address range, while the host portion identifies an individual device inside that range.<\/p>\n\n\n\n
A prefix length shows where the network portion ends and the host portion begins. For example, in The prefix length describes the size of the range. It does not mean that the subnet contains exactly 24 devices. An IPv4 Prefix notation is based on Classless Inter-Domain Routing, commonly called CIDR. You do not need to calculate binary values to understand the basic idea. In general, a smaller number after the slash represents a larger address range, while a larger number represents a smaller range.<\/p>\n\n\n\n For example:<\/p>\n\n\n\n Simple rule:<\/strong> The address before the slash identifies the network range, and the number after the slash describes its size.<\/p>\n<\/blockquote>\n\n\n\n IPv4 addresses contain 32 bits and are normally written as four decimal numbers separated by periods. An example is An IPv4 subnet is often written using a network address and prefix length, such as In a traditional local network, the first address is used as the network address and the last address is reserved for broadcast traffic. This leaves 254 addresses for ordinary devices. Cloud environments, point-to-point links, and specialised networks may use different rules, so the usable number is not always the same.<\/p>\n\n\n\n A The correct subnet size depends on the number of devices, expected growth, security requirements, and the overall network design.<\/p>\n\n\n\n IPv6 addresses contain 128 bits and are written using hexadecimal characters separated by colons. An example is IPv6 uses the same prefix concept as IPv4, but the much larger address space makes the planning model different. IPv6 networks are generally designed around clear and generous address boundaries rather than trying to conserve every individual address.<\/p>\n\n\n\n An IPv6 An IPv6 It is important to remember that an IPv4 The following module helps compare common IPv4 and IPv6 prefix sizes.<\/p>\n\n\n\n192.0.2.0\/24<\/code>, the \/24<\/code> indicates that the first 24 bits identify the network. The remaining bits are used for addresses within that subnet.<\/p>\n\n\n\n\/24<\/code> contains 256 total addresses, while an IPv6 \/48<\/code> represents an extremely large address range.<\/p>\n\n\n\n\n
192.0.2.0\/24<\/code> is an IPv4 subnet.<\/li>\n\n\n\n192.0.2.0\/25<\/code> is a smaller IPv4 subnet.<\/li>\n\n\n\n2001:db8:1234::\/48<\/code> is an IPv6 prefix.<\/li>\n\n\n\n2001:db8:1234:1200::\/64<\/code> is a smaller IPv6 subnet.<\/li>\n<\/ul>\n\n\n\n\n
IPv4 Subnets Explained<\/h2>\n\n\n\n
192.0.2.25<\/code>.<\/p>\n\n\n\n192.0.2.0\/24<\/code>. This range begins at 192.0.2.0<\/code> and ends at 192.0.2.255<\/code>, giving 256 total addresses.<\/p>\n\n\n\n\/24<\/code> is a familiar subnet size because it is suitable for many small offices, service networks, and VLANs. However, it is not always the correct choice. A \/25<\/code> divides the capacity of a \/24<\/code> into two smaller ranges, while a \/23<\/code> combines the capacity of two adjacent \/24<\/code> networks.<\/p>\n\n\n\nIPv6 Prefixes Explained<\/h2>\n\n\n\n
2001:db8:1234::1<\/code>.<\/p>\n\n\n\n\/48<\/code> is commonly used as an organisation-wide allocation. It can be divided into 65,536 separate \/64<\/code> subnets. A \/64<\/code> is widely used for one ordinary IPv6 LAN or VLAN because it supports common IPv6 address-configuration methods.<\/p>\n\n\n\n\/56<\/code> can be divided into 256 separate \/64<\/code> networks. This can be suitable for a smaller business, customer network, or site that needs several internal IPv6 segments.<\/p>\n\n\n\n\/48<\/code> and an IPv6 \/48<\/code> are not comparable. IPv4 and IPv6 use different address lengths and different operational planning conventions.<\/p>\n\n\n\nIPv4 and IPv6 Prefix Comparison<\/h2>\n\n\n\n