16 bits per block . 8 16bit blocks = 128bits
16 bits per block
In a Class A address, the default subnet mask is 255.0.0.0, allowing for a large number of hosts within a single network, but with 16 bits designated for the subnet ID, the subnet mask becomes 255.255.0.0. In contrast, a Class B address has a default subnet mask of 255.255.0.0, and with 8 bits for the subnet ID, the subnet mask would typically be 255.255.255.0. Thus, the key difference lies in the number of bits allocated for the subnet ID and the resulting subnet masks, affecting the number of available subnets and hosts per subnet.
To create a subnet ID, you start with the network's base IP address and subnet mask. The subnet mask determines how many bits are allocated for the network and how many for the hosts. By applying the subnet mask to the base IP address, you can identify the subnet ID, which represents the network portion of the address. For example, if your base IP is 192.168.1.0 with a subnet mask of 255.255.255.0, the subnet ID is 192.168.1.0.
16 bits per block
In IPv6, the multicast address subnet ID is 64 bits long. This is part of the overall 128-bit address structure, where the first 8 bits are reserved for the multicast prefix (FF00::/8), followed by 16 bits for flags and scope, and the remaining 64 bits represent the group ID. Thus, the group ID allows for a large number of multicast groups within the IPv6 space.
The subnet mask would be 255.255.255.0
To determine the number of bits in the subnetted ID of 185.27.54.0, you need to know the subnet mask used. However, if it’s a standard Class B address (which uses a default mask of 255.255.0.0), it has 16 bits for the network portion. If the address is subnetted further, additional bits are borrowed from the host portion, increasing the network bit count. For example, if a subnet mask of 255.255.255.0 is used, then there would be 24 bits in the subnetted ID.
Subnet mask.
Since a subnet mask is used to separate the network id from the host id, any 1 bits indicate the network portion and the 0 bits indicate host portion. As an example, in the subnet mask: 255.255.0.0 This indicates the first two octets are used for the network, and the last two octets (ipV4) are used for host portion of an address.
It depends on the book, but is usually known as the extended network prefix.
151.242.16.49 would be class B in a classful environment with a network mask of 16 bits. An additional 7 bit subnet mask puts the total mask at 23 (i.e.: 255.255.254). Subnet ID would be: 151.242.16.0 Host address range: 151.242.16.1 through 151.242.17.254 Subnet Broadcast address would be: 151.242.17.255
Since this is a class B network you have borrowed 8 bits for subnets. This leaves 8 bits left (1 octet) for clients/workstations. That gives you a maximum of 254 clients per subnet.