IP Address Calculator & Subnetting Tool
Calculate network addresses, subnet masks, and perform subnetting operations for IPv4 addresses. Perfect for network design and CCNA preparation.
IP Address Input
Quick Examples:
CIDR Notation Reference
/24
255.255.255.0
Hosts: 254
C
/25
255.255.255.128
Hosts: 126
C/2
/26
255.255.255.192
Hosts: 62
C/4
/27
255.255.255.224
Hosts: 30
C/8
/28
255.255.255.240
Hosts: 14
C/16
/29
255.255.255.248
Hosts: 6
C/32
/30
255.255.255.252
Hosts: 2
Point-to-Point
/16
255.255.0.0
Hosts: 65,534
B
Study Notes & Exam Tips
IP Address Classes (Historical)
- Class A: 1.0.0.0 to 126.255.255.255 (/8)
- Class B: 128.0.0.0 to 191.255.255.255 (/16)
- Class C: 192.0.0.0 to 223.255.255.255 (/24)
- Class D: 224.0.0.0 to 239.255.255.255 (Multicast)
- Class E: 240.0.0.0 to 255.255.255.255 (Reserved)
Private IP Ranges (RFC 1918)
- 10.0.0.0/8: 10.0.0.0 to 10.255.255.255
- 172.16.0.0/12: 172.16.0.0 to 172.31.255.255
- 192.168.0.0/16: 192.168.0.0 to 192.168.255.255
- 169.254.0.0/16: Link-local (APIPA)
Subnetting Quick Tips
- • 2^n = Number of subnets (n = subnet bits)
- • 2^h - 2 = Usable hosts (h = host bits)
- • Always subtract 2 for network & broadcast
- • /30 networks have only 2 usable hosts
- • VLSM allows different subnet sizes
Common Exam Questions
- • Calculate network address from IP/mask
- • Find number of subnets and hosts
- • Determine if two IPs are in same subnet
- • Design subnetting scheme for requirements
- • Convert between decimal and binary