My name is Tim. I'm currently taking a review course to prep for my CCNA. This question was taken verbatim from the CCNA Guide to Cisco Networking, Third Edition. "Which of the following accurately describe the Media Access Control (MAC) address?" The instructor's answer guide shows "C. MAC addresses contain 12 hexadecimal numbers." as one of the three correct answers. I took issue with that. MAC addresses are 48 bits long (i.e. 6 hexadecimal numbers). While the format shows 12 hex characters, hyphens or colons to show grouping separate each pair. Each pair of characters represents a single hexadecimal number. The delimiters (i.e. non alpha-numeric ASCII characters--including spaces) show that the characters between them are to be taken as a single quantity. In decimal individual numbers can be written 1 2 3 or 1, 2, 3 etc.; however, 123 is one number or quantity--one hundred twenty three. In much the same way E 4 B or E:4:B represents three individual hex numbers (i.e. 14, 4, 11); however, E4B represents 3,659 (in decimal). Am I wrong?