How To Internet & Network IP: Classes, Broadcast, and Multicast A guide to internet protocol address classes, broadcast, and multicast Share Pin Email Print Blend Images/Getty Images Internet & Network Basics The Wireless Connection Guides & Tutorials Installing & Upgrading Tips & Tricks Key Concepts What Are Bitcoins? by Bradley Mitchell An MIT graduate who brings years of technical experience to articles on SEO, computers, and wireless networking. Updated November 17, 2018 27 27 people found this article helpful It can be confusing to think of an IP address as being anything other than just a random string of numbers used on the internet and in local networks. The truth is that there's a lot going on behind the scenes to assign and limit IP addresses. IP classes are used to assist in assigning IP addresses to networks with different size requirements. The IPv4 IP address space can be subdivided into five address classes called Class A, B, C, D, and E. Each IP class consists of a contiguous subset of the overall IPv4 address range. One such class is reserved only for multicast addresses, which is a type of data transmission where more than one computer is addressed information at once. IP Address Classes and Numbering The values of the leftmost four bits of an IPv4 address determine its class. For example, all Class C addresses have the leftmost three bits set to 110, but each of the remaining 29 bits may be set to either 0 or 1 independently (as represented by an x in these bit positions): 110xxxxx xxxxxxxx xxxxxxxx xxxxxxxx Converting the above to dotted decimal notation, it follows that all Class C addresses fall in the range from 192.0.0.0 through 126.96.36.199. The table below describes the IP address values and ranges for each class. Note that some of the IP address space is excluded from Class E for special reasons as described further below. Class Leftmost bits Start of Range End of Range Total Addresses A 0xxx 0.0.0.0 127.255.255.255 2,147,483,648 B 10xx 188.8.131.52 184.108.40.206 1,073,741,824 C 110x 192.0.0.0 220.127.116.11 536,870,912 D 1110 18.104.22.168 22.214.171.124 268,435,456 E 1111 240.0.0.0 254.255.255.255 268,435,456 IPv4 Address Classes IP Address Class E and Limited Broadcast The IPv4 networking standard defines Class E addresses as reserved, meaning that they should not be used on IP networks. Some research organizations use Class E addresses for experimental purposes. However, devices that try to use these addresses on the internet will be unable to communicate properly since devices are not designed to process those kinds of addresses. A special type of IP address is the limited broadcast address 255.255.255.255. A network broadcast involves delivering a message from one sender to many recipients. Senders direct an IP broadcast to 255.255.255.255 to indicate all other nodes on the local area network (LAN) should pick up that message. This broadcast is "limited" in that it does not reach every node on the internet; only nodes on the LAN. Internet Protocol officially reserves the entire range of addresses from 255.0.0.0 through 255.255.255.255 for broadcast, and this range should not be considered part of the normal Class E range. IP Address Class D and Multicast The IPv4 networking standard defines Class D addresses as reserved for multicast. Multicast is a mechanism in Internet Protocol for defining groups of client devices and sending messages only to that group rather than to every device on the LAN (broadcast) or just one other node (unicast). Multicast is mainly used on research networks. Like with Class E, Class D addresses should not be used by ordinary nodes on the internet. Continue Reading 0.0.0.0: Why This IP Address Means Trouble What's the Default IP Address for Broadband Routers? Master the Secrets of the Subnet Mask 255.255.255.0 Why Don't Most Devices Use the 192.168.0.0 IP Address? Computer Networking 101: What Is Classless Inter-Domain Routing? Networking 101: What's an Internet Protocol (IP) Address? The Beginner's Guide to Internet Protocol: Subnet Masks and Subnetting What Is an IP Address & What Are the Different Kinds of IP Addresses? How to Fix A 169 IP Address Error Static IP Addresses: Everything You Need to Know Public IP vs. Private IP: Everything You Need to Know What Is IPv4 and IPv6? How to Broadcast on PS4 Easy Ways to Look Up an IP Address Troubleshoot Your Problems With Windows File and Printer Sharing Do You Have a MAC Address You Need to Trace?