Calculateur de sous-réseaux

Comment utiliser cet outil

1. 1

   Type an IPv4 address with a prefix length into the box, for example 192.168.1.0/24. The field is pre-filled with that example to start.

2. 2

   Read the results table as you type. The network and broadcast addresses, dotted-decimal subnet mask, first and last usable host, usable host count, and total address count appear immediately.

3. 3

   Adjust the prefix length (the number after the slash) to widen or narrow the subnet and watch the host counts change.

4. 4

   If you see an Invalid CIDR or Invalid IP message, fix the input. The prefix must be 0 to 32 and each of the four octets must be 0 to 255.

Qu'est-ce que le calculateur de sous-réseaux ?

Cas d'usage courants

• Sizing a subnet for an office VLAN by checking how many usable hosts a /26 or /25 provides before you assign it.

• Finding the network and broadcast addresses you must exclude when configuring a static DHCP address pool.

• Translating a CIDR prefix into the dotted-decimal subnet mask a router or firewall interface expects, for example /22 to 255.255.252.0.

• Confirming the usable host range when writing an access-control list or firewall rule for a specific subnet.

• Verifying that a /31 point-to-point link between two routers gives you exactly two usable addresses with no broadcast waste.

• Teaching or studying subnetting for a networking course or a CCNA exam by experimenting with prefixes and seeing host math update live.

Questions fréquentes