IPv4, IPv6 and MAC Addresses

IPv4 addresses contain 32 bits, commonly written as four decimal octets, each from 0 to 255. The teaching address 192.0.2.10 lies in an IPv4 documentation block; it is used here as an example rather than a live service target. IPv6 uses 128 bits, commonly displayed in hexadecimal groups with valid abbreviation rules.

A full IPv6 hexadecimal display can contain eight groups of sixteen bits, or thirty-two hexadecimal digits excluding separators. Hexadecimal is a written representation, not encryption or a different physical bit count. The raw number of 128-bit patterns is 2¹²⁸, compared with 2³² for IPv4, a ratio of 2⁹⁶. This is a mathematical comparison rather than a current count of Internet-connected devices.

IP addresses support network-layer addressing and routing in their relevant address domains. An interface may have several addresses, and private addresses can be reused in separate private networks. Routing and mechanisms such as NAT affect what addresses appear at different points. Do not claim that every displayed IP address uniquely identifies one person or one permanent physical device worldwide.

A common Ethernet MAC address has 48 bits, displayed as six hexadecimal octets. Link delivery uses relevant local addresses, while routers make network-layer forwarding decisions. A MAC address may be locally administered or randomised in a deployment; it should not be described as an immutable authentication credential. The address 02:00:00:00:00:01 can serve as a constructed locally administered teaching example.

A field with h unconstrained bits has 2ʰ possible patterns. For an IPv4 /24 prefix, eight remaining bits give 256 addresses in that block. A common conventional subnet exercise excludes a network address and broadcast address, yielding 254 assignable hosts under those explicit rules. That subtraction is not a universal rule for every IPv4 prefix or for IPv6.

Some address ranges are reserved for private, loopback, documentation or other special purposes. Allocation and protocol rules determine which patterns can serve which roles. In a question, establish the width, prefix and exclusions before writing the expression. Keep a MAC count, an IPv4 block count and the number of users or devices separate: none automatically equals the others.

Attempt the task before opening its worked response. Record each change of state, explain the rule used, and check the result against the original requirements. Code examples labelled Python 3 use that language’s conventions; pseudocode states its own assumptions.