188.8.131.52/24 is a network in CIDR notation. It encompasses all IP addresses between
You can get more explanation on CIDR easily by searching on the Internet, here is the quote from wikipedia:
CIDR notation is a compact representation of an IP address and its
associated routing prefix. The notation is constructed from an IP
address, a slash ('/') character, and a decimal number. The number is
the count of leading 1 bits in the routing mask, traditionally called
the network mask. The IP address is expressed according to the
standards of IPv4 or IPv6.
The address may denote a single, distinct interface address or the
beginning address of an entire network. The maximum size of the
network is given by the number of addresses that are possible with the
remaining, least-significant bits below the prefix. The aggregation of
these bits is often called the host identifier.
192.168.100.14/24 represents the IPv4 address 192.168.100.14 and its associated routing prefix 192.168.100.0, or equivalently, its subnet mask 255.255.255.0, which has 24 leading 1-bits.
the IPv4 block 192.168.100.0/22 represents the 1024 IPv4 addresses from 192.168.100.0 to 192.168.103.255.
the IPv6 block 2001:db8::/48 represents the block of IPv6 addresses from 2001:db8:0:0:0:0:0:0 to 2001:db8:0:ffff:ffff:ffff:ffff:ffff.
::1/128 represents the IPv6 loopback address. Its prefix size is 128, the size of the address itself.
Before the implementation of CIDR, IPv4 networks were represented by
the starting address and the subnet mask, both written in dot-decimal
notation. Thus, 192.168.100.0/24 was often written as
The number of addresses of a subnet may be calculated as 2^(address size
- prefix size), in which the address size is 128 for IPv6 and 32 for IPv4. For example, in IPv4, the prefix size /29 gives: 2^(32-29) = 2^3 = 8
You refer to "D class IP" , but classfull addressing is totally deprecated, for 20 years...