IP Address Class

My handy-dandy networking cheat sheet. Whether you’re a beginner or an experienced network administrator, this cheat sheet provides essential information on IP addressing, subnetting, protocols, and more.

	IP Range	Private IP Range	Subnet Mask	# of Networks	# of Hosts per Network
Class A	1.0.0.0 to 126.0.0.0	10.0.0.0 to 10.255.255.255	255.0.0.0	126	16,777,214
Class B	128.0.0.0 to 191.255.0.0	172.16.0.0 to 172.31.255.255	255.255.0.0	16,382	65,534
Class C	192.0.0.0 to 223.255.255.0	192.168.0.0 to 192.168.255.255	255.255.255.0	2,097,150	254
Class D	224.0.0.0 to 239.255.255.255	Multicasting	N/A	N/A	N/A
Class E	240.0.0.0 to 255.255.255.255	Research	N/A	N/A	N/A

undefined- For Class A, the correct IP range is 1.0.0.0 to 126.0.0.0. The range you provided includes the loop-back address range, which is not part of the Class A range.

• For Class D and Class E, the IP ranges you provided are correct. However, they are not used for assigning IP addresses to hosts in regular networking. Class D is reserved for multicast addresses, and Class E is reserved for research purposes.
• The subnet mask for Class D and Class E is not applicable, as they are not used for host addressing.
• The number of networks and hosts per network for Class D and Class E are not applicable, as they are not used for regular network addressing.
• The IP range 127.0.0.1 to 127.255.255.255 is reserved for loop-back addresses. These addresses are used for testing network functionality on an individual device and cannot be assigned to a device in a network.
• Automatic Private IP Addressing (APIPA) is a feature in Microsoft Windows that allows a computer to automatically assign itself an IP address within the range of 169.254.0.0 to 169.254.255.255 if a DHCP server is not available on the network.