I am new to Ethernet and Arduino.
I have read through most of the basics and am trying to get the first sketch to work.
How do I know if I should use 'zeros' or 'O's for the Mac address?
on my board it says 90-A2-etc, etc
Should I use "90-..." or "9O-..." See the difference? It would be handy to have this distinction in the tutorials on this site. I know there are others who have mentioned this I just haven't found a straight forward answer.
Apparently you always use the numerical symbol, not the alphabetical symbol.
Not exactly written on the wall.
As the numbers are all hexadecimal, they can only be 0 to 9 and A to F.
It does not need to be "written on the wall".
Weedpharma
If all else fails, Google "Mac address": MAC address - Wikipedia
The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), in transmission order (e.g. 01-23-45-67-89-ab or 01:23:45:67:89:ab ).
My emphasis.