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MAC addresses and network identifiers

Understand MAC notation, vendor-prefix lookup, local addressing, and EUI-64 conversion limits.

A prefix can identify an allocation, not a device owner

A vendor lookup compares an address prefix with registry data. Locally administered addresses, randomized identifiers, and registry coverage limits can make that result incomplete or misleading.

Treat notation and derivation as separate questions

Colon-separated, hyphen-separated, and dotted forms may encode the same 48 bits. A 64-bit interface identifier derived from a MAC uses a defined transformation, but modern IPv6 addressing can use other methods too.

Resources

MAC addresses and network identifiers

All field notes
Aa →fakeloc / Guides
NETWORK IDENTIFIERS

Locally administered vs. universal MAC addresses

Read the individual/group and universal/local bits without mistaking a prefix for a device identity.

Read the guide
{ … }fakeloc / Guides
NETWORK IDENTIFIERS

What a MAC vendor lookup can and cannot tell you

Use registry prefixes as allocation clues and explain the uncertainty around local or randomized addresses.

Read the guide
〒fakeloc / Guides
NETWORK IDENTIFIERS

MAC address formats and the EUI-64 relationship

Normalize common 48-bit text forms and understand the defined EUI-64 transformation.

Read the guide