System was with by Erreur32. ( in we trust ) Copyleft 2019
Netmask Netmask (binary) CIDR Notes
_____________________________________________________________________________
255.255.255.255 11111111.11111111.11111111.11111111 /32 Host (single addr)
255.255.255.254 11111111.11111111.11111111.11111110 /31 Unuseable
255.255.255.252 11111111.11111111.11111111.11111100 /30 2 useable
255.255.255.248 11111111.11111111.11111111.11111000 /29 6 useable
255.255.255.240 11111111.11111111.11111111.11110000 /28 14 useable
255.255.255.224 11111111.11111111.11111111.11100000 /27 30 useable
255.255.255.192 11111111.11111111.11111111.11000000 /26 62 useable
255.255.255.128 11111111.11111111.11111111.10000000 /25 126 useable
255.255.255.0 11111111.11111111.11111111.00000000 /24 "Class C" 254 useable
255.255.254.0 11111111.11111111.11111110.00000000 /23 2 Class C's
255.255.252.0 11111111.11111111.11111100.00000000 /22 4 Class C's
255.255.248.0 11111111.11111111.11111000.00000000 /21 8 Class C's
255.255.240.0 11111111.11111111.11110000.00000000 /20 16 Class C's
255.255.224.0 11111111.11111111.11100000.00000000 /19 32 Class C's
255.255.192.0 11111111.11111111.11000000.00000000 /18 64 Class C's
255.255.128.0 11111111.11111111.10000000.00000000 /17 128 Class C's
255.255.0.0 11111111.11111111.00000000.00000000 /16 "Class B"
255.254.0.0 11111111.11111110.00000000.00000000 /15 2 Class B's
255.252.0.0 11111111.11111100.00000000.00000000 /14 4 Class B's
255.248.0.0 11111111.11111000.00000000.00000000 /13 8 Class B's
255.240.0.0 11111111.11110000.00000000.00000000 /12 16 Class B's
255.224.0.0 11111111.11100000.00000000.00000000 /11 32 Class B's
255.192.0.0 11111111.11000000.00000000.00000000 /10 64 Class B's
255.128.0.0 11111111.10000000.00000000.00000000 /9 128 Class B's
255.0.0.0 11111111.00000000.00000000.00000000 /8 "Class A"
254.0.0.0 11111110.00000000.00000000.00000000 /7
252.0.0.0 11111100.00000000.00000000.00000000 /6
248.0.0.0 11111000.00000000.00000000.00000000 /5
240.0.0.0 11110000.00000000.00000000.00000000 /4
224.0.0.0 11100000.00000000.00000000.00000000 /3
192.0.0.0 11000000.00000000.00000000.00000000 /2
128.0.0.0 10000000.00000000.00000000.00000000 /1
0.0.0.0 00000000.00000000.00000000.00000000 /0 IP space
Net Host Total
Net Addr Addr Addr Number
Class Range NetMask Bits Bits of hosts
----------------------------------------------------------
A 0-127 255.0.0.0 8 24 16777216 (i.e. 114.0.0.0)
B 128-191 255.255.0.0 16 16 65536 (i.e. 150.0.0.0)
C 192-254 255.255.255.0 24 8 256 (i.e. 199.0.0.0)
D 224-239 (multicast)
E 240-255 (reserved)
F 208-215 255.255.255.240 28 4 16
G 216/8 ARIN - North America
G 217/8 RIPE NCC - Europe
G 218-219/8 APNIC
H 220-221 255.255.255.248 29 3 8 (reserved)
K 222-223 255.255.255.254 31 1 2 (reserved)
(ref: RFC1375 & http://www.iana.org/assignments/ipv4-address-space )
----------------------------------------------------------
The current list of special use prefixes:
0.0.0.0/8
127.0.0.0/8
192.0.2.0/24
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16
169.254.0.0/16
all D/E space
(ref: RFC1918 http://www.rfc-editor.org/rfc/rfc1918.txt )
(rfc search: http://www.rfc-editor.org/rfcsearch.html )
Martians: (updates at: www.iana.org/assignments/ipv4-address-space ) no ip source-route access-list 100 deny ip host 0.0.0.0 any deny ip 0.0.0.0 0.255.255.255 any log ! antispoof deny ip 0.0.0.0 0.255.255.255 0.0.0.0 255.255.255.255 ! antispoof deny ip any 255.255.255.128 0.0.0.127 ! antispoof deny ip host 0.0.0.0 any log ! antispoof deny ip host [router intf] [router intf] ! antispoof deny ip xxx.xxx.xxx.0 0.0.0.255 any log ! lan area deny ip 0/8 0.255.255.255 any log ! IANA - Reserved deny ip 1/8 0.255.255.255 any log ! IANA - Reserved deny ip 2/8 0.255.255.255 any log ! IANA - Reserved deny ip 5/8 0.255.255.255 any log ! IANA - Reserved deny ip 7/8 0.255.255.255 any log ! IANA - Reserved deny ip 10.0.0.0 0.255.255.255 any log ! IANA - Private Use deny ip 23/8 0.255.255.255 any log ! IANA - Reserved deny ip 27/8 0.255.255.255 any log ! IANA - Reserved deny ip 31/8 0.255.255.255 any log ! IANA - Reserved deny ip 36-37/8 0.255.255.255 any log ! IANA - Reserved deny ip 39/8 0.255.255.255 any log ! IANA - Reserved deny ip 41-42/8 0.255.255.255 any log ! IANA - Reserved deny ip 50/8 0.255.255.255 any log ! IANA - Reserved deny ip 58-60/8 0.255.255.255 any log ! IANA - Reserved deny ip 69-79/8 0.255.255.255 any log ! IANA - Reserved deny ip 82-95/8 0.255.255.255 any log ! IANA - Reserved deny ip 96-126/8 0.255.255.255 any log ! IANA - Reserved deny ip 127/8 0.255.255.255 any log ! IANA - Reserved deny ip 169.254.0.0 0.0.255.255 any log ! link-local network deny ip 172.16.0.0 0.15.255.255 any log ! reserved deny ip 192.168.0.0 0.0.255.255 any log ! reserved deny ip 192.0.2.0 0.0.0.255 any log ! test network deny ip 197/8 0.255.255.255 any log ! IANA - Reserved deny ip 220/8 0.255.255.255 any log ! IANA - Reserved deny ip 222-223/8 0.255.255.255 any log ! IANA - Reserved deny ip 224.0.0.0 31.255.255.255 any log ! multicast deny ip 224.0.0.0 15.255.255.255 any log ! unless MBGP-learned routes deny ip 224-239/8 0.255.255.255 any log ! IANA - Multicast deny ip 240-255/8 0.255.255.255 any log ! IANA - Reserved filtered source addresses 0/8 ! broadcast 10/8 ! RFC 1918 private 127/8 ! loopback 169.254.0/16 ! link local 172.16.0.0/12 ! RFC 1918 private 192.0.2.0/24 ! TEST-NET 192.168.0/16 ! RFC 1918 private 224.0.0.0/4 ! class D multicast 240.0.0.0/5 ! class E reserved 248.0.0.0/5 ! reserved 255.255.255.255/32 ! broadcast ARIN administrated blocks: (http://www.arin.net/regserv/IPStats.html) 24.0.0.0/8 (portions of) 63.0.0.0/8 64.0.0.0/8 65.0.0.0/8 66.0.0.0/8 196.0.0.0/8 198.0.0.0/8 199.0.0.0/8 200.0.0.0/8 204.0.0.0/8 205.0.0.0/8 206.0.0.0/8 207.0.0.0/8 208.0.0.0/8 209.0.0.0/8 216.0.0.0/8
Decimal system Prefix's
Factor Exponent Prefix
---------------------------------------------------
1 000 000 000 000 000 000 000 000...10^24....yotta
1 000 000 000 000 000 000 000...10^21....zetta
1 000 000 000 000 000 000...10^18....exa
1 000 000 000 000 000...10^15....peta
1 000 000 000 000...10^12....tera
1 000 000 000...10^9.....giga
1 000 000...10^6.....mega
1 000...10^3.....kilo
100...10^2.....hecto
10...10^1.....deka
0.1...10^-1....deci
0.01...10^-2....centi
0.001...10^-3....milli
0.000 001...10^-6....micro
0.000 000 001...10^-9....nano
0.000 000 000 001...10^-12...pico
0.000 000 000 000 001...10^-15...femto
0.000 000 000 000 000 001...10^-18...atto
0.000 000 000 000 000 000 001...10^-21...zepto
0.000 000 000 000 000 000 000 001...10^-24...yocto
---------------------------------------------------
Convert Fahrenheit <> Celsius:
Celsius = (Fahrenheit - 32) / 1.8
Fahrenheit = (Celsius * 1.8) + 32