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Subnet Mask Calculator

Enter the TCPIP Network Address:
Force as Class: Default Class A Class B Class C
Enter the required number of sub-networks:
OR enter the required number of nodes/hosts per network:
Network Class:
Subnet Mask: or
Nodes/Hosts per Network:

Network/Node Calculator

Enter the Subnet Mask:
Enter the TCPIP Address:
Broadcast Address:

IP Address Converter

Enter the dotted decimal TCPIP Address:
or Enter the binary TCPIP Address:
or Enter the hex TCPIP Address:
or Enter the decimal TCPIP Address:




IP or Name: 




IP or Name:


Domain Name Service 
(lookup full SOA, IP, NS, MX records)

Enter domain name ie.: mobrien.com

  1. Dig 8.3 Query
  2. Host Query
  3. NSLookup
  4. Trace
  5. Trace Resources
  6. Routing Calculator
  7. Whois

Three Network Classes

In a 32-bit IP address, the number of bits used to identify the network and the host vary according to the network class of the address. In a Class C network, the first 3 bits, or the high-order bits, are always "110." The next 21 bits are used to define the Class C network, and the final eight bits are used to identify the host. The IP address is represented in dotted decimal notation of four 8-bit fields, or octets, that have been converted from binary to decimal numbers. The following refers to "decimal numbers".

Class C Networks

This is the most widely used class by small businesses. When you look at the IP address, you'll notice that class C networks start with a first number that's between 192 and 223 (205.161.74.x for example). There can be up to 2,097,151 class C networks and each network can handle close to 254 computers.

Class B Networks

IP addresses of this type starts with a number between 128 and 191. It's possible to have 16,384 of these networks and each class B network can handle up to 65,534 IP addresses or computers.

Class A Networks

Starts with a number between 1 and 126. Only 126 of these networks are available, however each class A network can handle 16,777,214 IP addresses or computers.

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