tailieunhanh - CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 43

Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 43 is the Cisco approved textbook to use alongside version of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | Page 389 Tuesday May 20 2003 2 53 PM IP Addresses 389 Decimal and Binary Conversion There is usually more than one way to solve a math problem and decimal-to-binary conversion is no exception. This section explores one method but feel free to use another method if it is easier. To convert a decimal number to binary the idea is to first find the biggest power of 2 that fits into the decimal number as shown in Table 7-1. If this process is designed to work with computers the most logical place to start is with the largest values that fit into 1 or 2 bytes. Table 7-1 Calculating Available Host Addresses 215 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 32678 16384 8192 4096 2048 1024 512 256 128 64 32 16 8 4 2 1 As mentioned the most common grouping of bits is 8 which make up one byte. But sometimes the largest value that can be held in 1 byte 255 is not large enough for the values needed. In this situation you must combine bytes so instead of having two 8-bit numbers you have one 16-bit number or instead of three 8-bit numbers you have one 24-bit number. The same rules apply as for 8-bit numbers You multiply the previous position value by 2 to get the present column value. Table 7-1 documents these values starting with a 2-byte 16-bit number which are very important when you re learning the mechanics of subnetting. Because working with computers often is referenced by bytes it is easiest to start with byte boundaries and calculate from there as shown in Table 7-2. To better demonstrate look at the next couple of calculation examples the first being 6 783. Because this number is greater than 255 the largest value possible in a single byte you use 2 bytes. Start calculating from 215. The result is that 6 783 equals 00011010 01111111. Table 7-2 Decimal-to-Binary Conversion Chart Position Power Decimal Value Position Value Binary Count Remainder 215 6783 32678 0 6783 214 6783 16384 0 6783 213 6783 8192 0 6783 212 6783 4096 1 2687 continues Page .

• Chứng chỉ quốc tế
• Luyện thi CCNA
• kỹ năng xử lý sự cố
• chương trình học viện mạng Cisco
• làm quen với quản trị mạng
• công nghệ Ethernet
• TCP IP
• phương tiện truyền thông mạng IP
• địa chỉ IP
• định tuyến giao thức
• chứng chỉ CCNA
• trắc nghiệm CCNA
• bài tập CCNA
• tài liệu CCNA
• Giáo trình CCNA
• Phần mềm CISCO
• Lập trình mạng
• CCNA1 Practice Final
• quản trị mạng
• luyện thi chứng chỉ quốc tế
• chương trình Cisco