MAC address 00:1B:C5:0 details

Assigned Prefix
00:1B:C5:0

28-bit Prefix (IEEE Standard)

Block Base Allocation
N/A

Hardware Interface 0x00000 (Min)

Block Top Boundary
N/A

Hardware Interface 0xFFFFF (Max)

Network Addressing & Host Scope

28-Bit Prefix

This assignment represents an IEEE standard allocation, granting a dedicated boundary of 1,048,576 unique host MAC addresses.

START: 1,048,576 Total Addresses END:
Lower Bound (Base Host 0) Upper Bound (Top Boundary)
IEEE Registry Tier IEEE Standard Universally Administered (UAA)
Total Host Capacity 1,048,576 Exact binary space: 220 addresses
Derived IPv6 Link-Local SLAAC Base RFC 4291 EUI-64
fe80::021b:c5ff:fe00:0000

Base address derived from the allocation start, not a network prefix or a verified configured address. The link-local subnet is fe80::/64.

RFC 4291 (Modified EUI-64): This example derives an interface identifier from a 48-bit MAC address by inserting ff:fe and inverting the universal/local bit. An interface can use a different IPv6 identifier.

Octet & Bit Architecture

28-Bit Architecture
Allocation Spread 28-BIT PREFIX (58%) + 20-BIT HOST (42%)
28-Bit Prefix
20-Bit Host
Bit 0 [00:1B:C5:0]
Bit 28
Bit 47 [Host Top]

OUI / Prefix OUI means Organizationally Unique Identifier. MA-L uses a 24-bit prefix; MA-M and MA-S use 28-bit and 36-bit prefixes.

Host bits The remaining bits define the address space within the allocation.

Binary Octet Breakdown (Prefix)

Colored bits in Octet 0 (the first byte) match the I/G and U/L cards below. Octet indices start at zero.

Octet 0 00 0000 00 0 0
Octet 1 1B 0001 1011
Octet 2 C5 1100 0101
Octet 3 (high nibble) 0_ 0000 [Host]
First octet, bit 1 (U/L) b1 = 0
Universally Administered (UAA)

Globally unique IEEE governed address.

First octet, bit 0 (I/G) b0 = 0
Unicast Transmission

Individual address destination (point-to-point transmission).

Wireshark Dissector Intel Matches Found
Display Filter: eth.addr[0:3] == 00:1b:c5 && (eth.addr[3] & 0xf0) == 0x00
Vendor Tags: Converging Systems Inc.

REST API v2

200 OK
CLI curl -s https://api.maclookup.app/v2/macs/001bc50 -H 'Accept: application/json'
{
  "success": true,
  "found": true,
  "macPrefix": "001BC50",
  "company": "",
  "address": "",
  "country": "",
  "blockStart": "",
  "blockEnd": "",
  "blockSize": 0,
  "blockType": "",
  "updated": "",
  "isRand": false,
  "isPrivate": false
}