| Choosing a realistic example is always problematic: I recall having problems | with the OS/2 documents which use a class A network (IBM's( as the example. | Might be a good one for those enterprises large enough to HAVE a class A | network. | +---->> Perhaps this table will help some of you. It contains both CIDR and netmask values in HEX (easier to translate to binary) and the standard decimal notation as well as the "Classful" A,B,C. The second part of the table is for handling and setting up subnets. You need to understand that all the netmasks are actually binary ANDs and that subnets MUST break on binary boundaries. Mask value: # of Hex CIDR Decimal addresses Classfull 80.00.00.00 /1 128.0.0.0 2048 M 128 A C0.00.00.00 /2 192.0.0.0 1024 M 64 A E0.00.00.00 /3 224.0.0.0 512 M 32 A F0.00.00.00 /4 240.0.0.0 256 M 16 A F8.00.00.00 /5 248.0.0.0 128 M 8 A FC.00.00.00 /6 252.0.0.0 64 M 4 A FE.00.00.00 /7 254.0.0.0 32 M 2 A FF.00.00.00 /8 255.0.0.0 16 M 1 A FF.80.00.00 /9 255.128.0.0 8 M 128 B FF.C0.00.00 /10 255.192.0.0 4 M 64 B FF.E0.00.00 /11 255.224.0.0 2 M 32 B FF.F0.00.00 /12 255.240.0.0 1024 K 16 B FF.F8.00.00 /13 255.248.0.0 512 K 8 B FF.FC.00.00 /14 255.252.0.0 256 K 4 B FF.FE.00.00 /15 255.254.0.0 128 K 2 B FF.FF.00.00 /16 255.255.0.0 64 K 1 B FF.FF.80.00 /17 255.255.128.0 32 K 128 C FF.FF.C0.00 /18 255.255.192.0 16 K 64 C FF.FF.E0.00 /19 255.255.224.0 8 K 32 C FF.FF.F0.00 /20 255.255.240.0 4 K 16 C FF.FF.F8.00 /21 255.255.248.0 2 K 8 C FF.FF.FC.00 /22 255.255.252.0 1 K 4 C FF.FF.FE.00 /23 255.255.254.0 512 2 C FF.FF.FF.00 /24 255.255.255.0 256 1 C FF.FF.FF.80 /25 255.255.255.128 128 1/2 C FF.FF.FF.C0 /26 255.255.255.192 64 1/4 C FF.FF.FF.E0 /27 255.255.255.224 32 1/8 C FF.FF.FF.F0 /28 255.255.255.240 16 1/16 C FF.FF.FF.F8 /29 255.255.255.248 8 1/32 C FF.FF.FF.FC /30 255.255.255.252 4 1/64 C FF.FF.FF.FE /31 255.255.255.254 2 1/128 C FF.FF.FF.FF /32 255.255.255.255 This is a single host route | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| A| B| C| D| E| F|HI/HEX O H | 00| 02| 04| 06| 10| 12| 14| 16| 20| 22| 24| 26| 30| 32| 34| 36| /OCT C E |0000|0001|0010|0011|0100|0101|0110|0111|1000|1001|1010|1011|1100|1101|1110|1111|/BINARYT X |----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----------- | 0.| 16.| 32.| 48.| 64.| 80.| 96.|112.|128.|144.|160.|176.|192.|208.|224.|240.|0000b 0o 0h | 1.| 17.| 33.| 49.| 65.| 81.| 97.|113.|129.|145.|161.|177.|193.|209.|225.|241.|0001b 1o 1h | 2.| 18.| 34.| 50.| 66.| 82.| 98.|114.|130.|146.|162.|178.|194.|210.|226.|242.|0010b 2o 2h | 3.| 19.| 35.| 51.| 67.| 83.| 99.|115.|131.|147.|163.|179.|195.|211.|227.|243.|0011b 3o 3h |----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----------- | 4.| 20.| 36.| 52.| 68.| 84.|100.|116.|132.|148.|164.|180.|196.|212.|228.|244.|0100b 4o 4h | 5.| 21.| 37.| 53.| 69.| 85.|101.|117.|133.|149.|165.|181.|197.|213.|229.|245.|0101b 5o 5h | 6.| 22.| 38.| 54.| 70.| 86.|102.|118.|134.|150.|166.|182.|198.|214.|230.|246.|0110b 6o 6h | 7.| 23.| 39.| 55.| 71.| 87.|103.|119.|135.|151.|167.|183.|199.|215.|231.|247.|0111b 7o 7h |====|====|====|====|====|====|====|====|====|====|====|====|====|====|====|====|============= | 8.| 24.| 40.| 56.| 72.| 88.|104.|120.|136.|152.|168.|184.|200.|216.|232.|248.|1000b 0o 8h | 9.| 25.| 41.| 57.| 73.| 89.|105.|121.|137.|153.|169.|185.|201.|217.|233.|249.|1001b 1o 9h | 10.| 26.| 42.| 58.| 74.| 90.|106.|122.|138.|154.|170.|186.|202.|218.|234.|250.|1010b 2o Ah | 11.| 27.| 43.| 59.| 75.| 91.|107.|123.|139.|155.|171.|187.|203.|219.|235.|251.|1011b 3o Bh |----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|---------- | 12.| 28.| 44.| 60.| 76.| 92.|108.|124.|140.|156.|172.|188.|204.|220.|236.|252.|1100b 4o Ch | 13.| 29.| 45.| 61.| 77.| 93.|109.|125.|141.|157.|173.|189.|205.|221.|237.|253.|1101b 5o Dh | 14.| 30.| 46.| 62.| 78.| 94.|110.|126.|142.|158.|174.|190.|206.|222.|238.|254.|1110b 6o Eh | 15.| 31.| 47.| 63.| 79.| 95.|111.|127.|143.|159.|175.|191.|207.|223.|239.|255.|1111b 7o Fh |----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|---------- | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| A| B| C| D| E| F|HI/ O H | 01| 03| 05| 07| 11| 13| 15| 17| 21| 23| 25| 27| 31| 33| 35| 37| / C E |0000|0001|0010|0011|0100|0101|0110|0111|1000|1001|1010|1011|1100|1101|1110|1111|/LOW T X -- Robert E. Gunn|Post Office Box 27474 |Voice:+1 713 960 1588 <>|Houston, Texas 77227-7474|Fax: +1 713 960 9497