Cisco Numbers and Patterns to Remember
Prepared by Floyd Winters for the Manatee Community College Cisco Program June 2000
	Binary	Ports	Updates	ACLs		HOME
				8	7	6	5	4	3	2	1
Decimal	Binary		Bit Number:	1	1	1	1	1	1	1	1	Eight 1's in binary = 255
1	0001		Bit Value:	128	64	32	16	8	4	2	1	255	= Sum Left to Right
2	0010	2^1	Start Class B	128	128	64	32	16	8	4	2
3	0011		Start Class C		192	128	64	32	16	8	4
4	0100	2^2	Start Class D			224	128	64	32	16	8
5	0101		Start Class E				240	128	64	32	16
6	0110							248	128	64	32
7	0111								252	128	64
8	1000	2^3 looks like 10^3, which is 1,000 or 10x10x10								254	128
9	1001										255	= Sum Top to Bottom
10	1010
11	1011
12	1100
13	1101
14	1110
15	1111
16	10000	2^4 looks like 10^4, which is 10,000 or 10x10x10x10
256	100000000	2^8	Number of possible hosts for 8 bits or one Octect: 255 plus 1 for the zero position
1,024		2^10	K = 2 to 10th or 1 with 10 zeros after it
65,536		2^16	2 Octects of Hosts or 64K
1,048,576		2^20	Meg = 2 to 20th or 1 with 20 zeros after it
16,777,216		2^24	3 Octects of Hosts in Class A; also 24-bit Bit Map: 16 Million possible hosts or colors
1,073,741,824		2^30	Gig
	Binary		Top of Page			HOME
Ports #s:	Protocol		Update Time:	Protocol		Access Control List Ranges
20	FTP-Data		30	RIP		1-99			IP
21	FTP		60	CDP		100-199			Extended IP
23	TELNET		90	IGRP		600-699			Appletalk
25	SMTP					800-899			IPX
69	TFTP					900-999			Extended IPX
80	HTTP					1000-1099			IPX Service Advertizing