An IPv4 address class is a categorical division of internet protocol addresses in IPv4-based routing. Show
Separate IP classes are used for different types of networks. Some are used for public internet-accessible IPs and subnets, that is, those networks behind a router (as in classes A, B and C). As well, some classes are reserved by the Internet Engineering Task Force (IETF) and the Internet Assigned Numbers Authority (IANA) for specific purposes. These special ranges are used for multicasting of identical data to all computers on a network or subnet or for research (as in classes D, E). Within this notation, classes are mainly differentiated by the number of bits they have for the network and the number of bits used for hosts. IP addresses are notated in four groups of three-digit representations of 8 bits of binary in base 10-formatted notation for a total of 32 bits. The groups are separated by periods starting from zero (which in binary would be 00000000); the highest number in a grouping is 255 (or 11111111). IPv4 address classes: Class A IP addresses, where the 1st bit is 0, encompass the range of 0.0.0.0 to 127.255.255.255. This class is for large networks and has 8 bits for network and 24 bits for hosts. Class B IP addresses, where the 1st two bits are 10, are in the range of 128.0.0.0 to 191.255.255.255. This class is for medium networks and has 16 bits for network and 16 bits for hosts. Class C IP addresses, where the 1st three bits are 110, are in the range of 192.0.0.0 to 223.255.255.255. This class is for smaller networks and has 24 bits for network and 8 bits for hosts. Class D or multicast IP addresses, where the 1st four bits are 1110 are in the range of 224.0.0.0 to 239.255.255.255 Class E or experimental IP addresses, where the 1st four bits are 11110, are in the range of 240.0.0.0 to 255.255.255.255. Prior to the introduction of IPv6 as a solution to the internet’s running out of addresses, the idea of opening the class E addresses was hotly debated. While forming the basis for IP address assignment, the system of IP address classes described here is generally bypassed today by use of Classless Inter-Domain Routing (CIDR) addressing. This was last updated in October 2020 Continue Reading About IPv4 address class
Related TermsAS/400 (IBM iSeries, AS/400e, eServer iSeries/400, Power Systems)The IBM Application System/400 -- or AS/400 -- is a family of midrange computers that was released in 1988, succeeding both ... See complete definitioniterative DNS queryAn iterative DNS query is a request for a website name or URL. See complete definitionnetwork switchA network switch connects devices in a network to each other, enabling them to talk by exchanging data packets. See complete definitionWord of the Day data dictionaryA data dictionary is a collection of descriptions of the data objects or items in a data model to which programmers and others can refer. An IP (Internet Protocol) address is a numerical label assigned to the devices connected to a computer network that uses the IP for communication. IP address act as an identifier for a specific machine on a particular network. It also helps you to develop a virtual connection between a destination and a source. The IP address is also called IP number or internet address. It helps you to specify the technical format of the addressing and packets scheme. Most networks combine TCP with IP. An IP address consists of four numbers, each number contains one to three digits, with a single dot (.) separates each number or set of digits.  IP Address is divided into two parts:
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IP Header Classes:ClassAddress RangeSubnet maskingExample IPLeading bitsMax number of networksApplicationIP Class A1 to 126255.0.0.01.1.1.18128Used for large number of hosts.IP Class B128 to 191255.255.0.0128.1.1.11616384Used for medium size network.IP Class C192 to 223255.255.255.0192.1.11.242097157Used for local area network.IP Class D224 to 239NANANANAReserve for multi-tasking.IP Class E240 to 254NANANANAThis class is reserved for research and Development Purposes.How does IP address work?IP address works in an IP network like a postal address. For example, a postal address combines two addresses, address, or your area your house address. The address or your area is a group address of all houses that belong to a specific area. The house address is the unique address of your homes in that area. Here, your area is represented by a PIN code number. In this example, the network address comprises all hosts which belong to a specific network. The host address is the unique address of a particular host in that network. What is Classful Addressing?Classful addressing is a network addressing the Internet’s architecture from 1981 till Classless Inter-Domain Routing was introduced in 1993. This addressing method divides the IP address into five separate classes based on four address bits. Here, classes A, B, C offers addresses for networks of three distinct network sizes. Class D is only used for multicast, and class E reserved exclusively for experimental purposes. Let’s see each of the network classes in detail: Class A NetworkThis IP address class is used when there are a large number of hosts. In a Class A type of network, the first 8 bits (also called the first octet) identify the network, and the remaining have 24 bits for the host into that network. An example of a Class A address is 102.168.212.226. Here, “102” helps you identify the network and 168.212.226 identify the host. Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and diagnostic functions. Class B NetworkIn a B class IP address, the binary addresses start with 10. In this IP address, the class decimal number that can be between 128 to 191. The number 127 is reserved for loopback, which is used for internal testing on the local machine. The first 16 bits (known as two octets) help you identify the network. The other remaining 16 bits indicate the host within the network. An example of Class B IP address is 168.212.226.204, where *168 212* identifies the network and *226.204* helps you identify the Hut network host. Class C NetworkClass C is a type of IP address that is used for the small network. In this class, three octets are used to indent the network. This IP ranges between 192 to 223. In this type of network addressing method, the first two bits are set to be 1, and the third bit is set to 0, which makes the first 24 bits of the address them and the remaining bit as the host address. Mostly local area network used Class C IP address to connect with the network. Example for a Class C IP address: 192.168.178.1 Class D NetworkClass D addresses are only used for multicasting applications. Class D is never used for regular networking operations. This class addresses the first three bits set to “1” and their fourth bit set to use for “0”. Class D addresses are 32-bit network addresses. All the values within the range are used to identify multicast groups uniquely. Therefore, there is no requirement to extract the host address from the IP address, so Class D does not have any subnet mask. Example for a Class D IP address: 227.21.6.173 Class E NetworkClass E IP address is defined by including the starting four network address bits as 1, which allows you two to incorporate addresses from 240.0.0.0 to 255.255.255.255. However, E class is reserved, and its usage is never defined. Therefore, many network implementations discard these addresses as undefined or illegal. How many hosts does Class C IP address have?A Class C address consists of a 24-bit network address and an 8-bit local host address. The first three bits in the network address indicate the network class, leaving 21 bits for the actual network address. Therefore, there are 2,097,152 possible network addresses and 256 possible local host addresses.
What is the size of host in Class B IP address?A class B network number uses 16 bits for the network number and 16 bits for host numbers.
How many valid hosts are usable in a Class B IP address?Class B IP addresses range from 128.0.0.0 to 191.255.255.255 , with a default subnet mask of 255.255.0.0 (or /16 in CIDR). Class B addressing can have 16,384 (214) network addresses and 65,534 (216) usable addresses per network.
How many hosts per network can exist in each of the IP address classes a B and C?This makes possible a maximum of 2,097,152 networks, each of which can have a maximum of 254 hosts.
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