I just want to share my knowledge i learned about it yesterday , When we see mac address table on switch we will see almost 20 mac address static, most people like me don't know What do the following mac addresses refer to, and here i found answer.
mac add in switch i mansion a few of them
SW#show mac address-table | include CPU
All 0100.0ccc.cccc STATIC CPU - Multicast address for CDP VTP DTP
All 0100.0ccc.cccd STATIC CPU - Multicast address for PVST
All 0180.c200.0000 STATIC CPU - Multicast address for STP
All 0180.c200.0001 STATIC CPU
All 0180.c200.0002 STATIC CPU
All 0180.c200.0003 STATIC CPU
All 0180.c200.0004 STATIC CPU
All 0180.c200.0005 STATIC CPU
All 0180.c200.0006 STATIC CPU
All 0180.c200.0007 STATIC CPU
All 0180.c200.0008 STATIC CPU
All 0180.c200.0009 STATIC CPU
All 0180.c200.000a STATIC CPU
All 0180.c200.000b STATIC CPU
All 0180.c200.000c STATIC CPU
All 0180.c200.000d STATIC CPU
All 0180.c200.000e STATIC CPU
All 0180.c200.000f STATIC CPU
All 0180.c200.0010 STATIC CPU
All ffff.ffff.ffff STATIC CPU
here link where i found them
https://en.wikipedia.org/wiki/Multicast_address#cite_note-15
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