Subnet Toolsand other network tips

Subnet Cheat Sheet

IP Multicast address ranges

All multicast addresses can easily be recognized because they
start with the bit pattern “1110”.
224.0.0.0 – 224.0.0.255 Well-known multicast addresses, control channels
224.0.1.0 – 238.255.255.255 Globally-scoped (Internet-wide) multicast addresses
239.0.0.0 – 239.255.255.255 Local multicast addresses

Special and private address ranges

Private address ranges are not routed on the Internet and can be freely allocated in any private network. NAT (network address translation) is required when connecting such a network to the Internet.

Private network addresses (RFC1597/RFC1918 addresses):
10.0.0.0 – 10.255.255.255 A 24-bit block, /8, class A network
172.16.0.0 – 172.31.255.255 A 20-bit block, /12, set of 16 contiguous class B network numbers
192.168.0.0 – 192.168.255.255 A 16-bit block, /16, set of 255 contiguous
class C network numbers

Special addresses:
127.0.0.0 – 127.255.255.255 Special address range for the localhost. You can normally not use those addresses for anything else.
127.0.0.1 is generally assigned to the loopback device

0.0.0.0 Special host address commonly reserved for the default route

 

Overview of common subnets and masks

Mask Hosts  Usable Netmask          Hex Mask
/30  4      2      255.255.255.252  fffffffc  
/29  8      6      255.255.255.248  fffffff8  
/28  16     14     255.255.255.240  fffffff0  
/27  32     30     255.255.255.224  ffffffe0  
/26  64     62     255.255.255.192  ffffffc0  
/24  256    254    255.255.255.0    ffffff00  
/23  512    510    255.255.254.0    fffffe00  
/22  1024   1022   255.255.252.0    fffffc00  
/21  2048   2046   255.255.248.0    fffff800  
/20  4096   4094   255.255.240.0    fffff000  
/19  8192   8190   255.255.224.0    ffffe000  
/18  16384  16382  255.255.192.0    ffffc000  
/17  32768  32766  255.255.128.0    ffff8000  
/16  65536  65534  255.255.0.0      ffff0000

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