This is very useful if you can't remember netmask or how much IP's are usable and belongs IP block.
| IP/CIDR |
Δ to last IP addr |
Mask |
Hosts (*) |
Size |
Notes |
| a.b.c.d/32 |
+0.0.0.0 |
255.255.255.255 |
1 |
1/256 C |
|
| a.b.c.d/31 |
+0.0.0.1 |
255.255.255.254 |
2 |
1/128 C |
d = 0 … (2n) … 254 |
| a.b.c.d/30 |
+0.0.0.3 |
255.255.255.252 |
4 |
1/64 C |
d = 0 … (4n) … 252 |
| a.b.c.d/29 |
+0.0.0.7 |
255.255.255.248 |
8 |
1/32 C |
d = 0 … (8n) … 248 |
| a.b.c.d/28 |
+0.0.0.15 |
255.255.255.240 |
16 |
1/16 C |
d = 0 … (16n) … 240 |
| a.b.c.d/27 |
+0.0.0.31 |
255.255.255.224 |
32 |
⅛ C |
d = 0 … (32n) … 224 |
| a.b.c.d/26 |
+0.0.0.63 |
255.255.255.192 |
64 |
¼ C |
d = 0, 64, 128, 192 |
| a.b.c.d/25 |
+0.0.0.127 |
255.255.255.128 |
128 |
½ C |
d = 0, 128 |
| a.b.c.0/24 |
+0.0.0.255 |
255.255.255.000 |
256 |
1 C |
|
| a.b.c.0/23 |
+0.0.1.255 |
255.255.254.000 |
512 |
2 C |
c = 0 … (2n) … 254 |
| a.b.c.0/22 |
+0.0.3.255 |
255.255.252.000 |
1,024 |
4 C |
c = 0 … (4n) … 252 |
| a.b.c.0/21 |
+0.0.7.255 |
255.255.248.000 |
2,048 |
8 C |
c = 0 … (8n) … 248 |
| a.b.c.0/20 |
+0.0.15.255 |
255.255.240.000 |
4,096 |
16 C |
c = 0 … (16n) … 240 |
| a.b.c.0/19 |
+0.0.31.255 |
255.255.224.000 |
8,192 |
32 C |
c = 0 … (32n) … 224 |
| a.b.c.0/18 |
+0.0.63.255 |
255.255.192.000 |
16,384 |
64 C |
c = 0, 64, 128, 192 |
| a.b.c.0/17 |
+0.0.127.255 |
255.255.128.000 |
32,768 |
128 C |
c = 0, 128 |
| a.b.0.0/16 |
+0.0.255.255 |
255.255.000.000 |
65,536 |
256 C = 1 B |
|
| a.b.0.0/15 |
+0.1.255.255 |
255.254.000.000 |
131,072 |
2 B |
b = 0 … (2n) … 254 |
| a.b.0.0/14 |
+0.3.255.255 |
255.252.000.000 |
262,144 |
4 B |
b = 0 … (4n) … 252 |
| a.b.0.0/13 |
+0.7.255.255 |
255.248.000.000 |
524,288 |
8 B |
b = 0 … (8n) … 248 |
| a.b.0.0/12 |
+0.15.255.255 |
255.240.000.000 |
1,048,576 |
16 B |
b = 0 … (16n) … 240 |
| a.b.0.0/11 |
+0.31.255.255 |
255.224.000.000 |
2,097,152 |
32 B |
b = 0 … (32n) … 224 |
| a.b.0.0/10 |
+0.63.255.255 |
255.192.000.000 |
4,194,304 |
64 B |
b = 0, 64, 128, 192 |
| a.b.0.0/9 |
+0.127.255.255 |
255.128.000.000 |
8,388,608 |
128 B |
b = 0, 128 |
| a.0.0.0/8 |
+0.255.255.255 |
255.000.000.000 |
16,777,216 |
256 B = 1 A |
|
| a.0.0.0/7 |
+1.255.255.255 |
254.000.000.000 |
33,554,432 |
2 A |
a = 0 … (2n) … 254 |
| a.0.0.0/6 |
+3.255.255.255 |
252.000.000.000 |
67,108,864 |
4 A |
a = 0 … (4n) … 252 |
| a.0.0.0/5 |
+7.255.255.255 |
248.000.000.000 |
134,217,728 |
8 A |
a = 0 … (8n) … 248 |
| a.0.0.0/4 |
+15.255.255.255 |
240.000.000.000 |
268,435,456 |
16 A |
a = 0 … (16n) … 240 |
| a.0.0.0/3 |
+31.255.255.255 |
224.000.000.000 |
536,870,912 |
32 A |
a = 0 … (32n) … 224 |
| a.0.0.0/2 |
+63.255.255.255 |
192.000.000.000 |
1,073,741,824 |
64 A |
a = 0, 64, 128, 192 |
| a.0.0.0/1 |
+127.255.255.255 |
128.000.000.000 |
2,147,483,648 |
128 A |
a = 0, 128 |
| 0.0.0.0/0 |
+255.255.255.255 |
000.000.000.000 |
4,294,967,296 |
256 A |
Also please look there:
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 )
( http://www.iana.org/numbers.htm )
----------------------------------------------------------
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 )
( or ftp://ftp.isi.edu/in-notes/rfc1918.txt )
(rfc search: http://www.rfc-editor.org/rfcsearch.html )
( http://www.ietf.org/ietf/1id-abstracts.txt )
( http://www.ietf.org/shadow.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
----------------------------------------------------------
well known ports: (rfc1700.txt)
www.iana.org/assignments/port-numbers
protocol numbers:
www.iana.org/assignments/protocol-numbers
www.iana.org/numbers.htm
ICMP(Types/Codes)
Testing Destination Reachability & Status
(0/0) Echo-Reply
(8/0) Echo
Unreachable Destinations
(3/0) Network Unreachable
(3/1) Host Unreachable
(3/2) Protocol Unreachable
(3/3) Port Unreachable
(3/4) Fragmentaion Needed and DF set (Pkt too big)
(3/5) Source Route Failed
(3/6) Network Unknown
(3/7) Host Unknown
(3/9) DOD Net Prohibited
(3/10) DOD Host Prohibited
(3/11) Net TOS Unreachable
(3/12) Host TOS Unreachable
(3/13) Administratively Prohibited
(3/14) Host Precedence Unreachable
(3/15) Precedence Unreachable
Flow Control
(4/0) Source-Quench [RFC 1016]
Route Change Requests from Gateways
(5/0) Redirect Datagrams for the Net
(5/1) Redirect Datagrams for the Host
(5/2) Redirect Datagrams for the TOS and Net
(5/3) Redirect Datagrams for the TOS and Host
Router
(6/-) Alternate-Address
(9/0) Router-Advertisement
(10/0) Router-Solicitation
Detecting Circular or Excessively Long Routes
(11/0) Time to Live Count Exceeded
(11/1) Fragment Reassembly Time Exceeded
Reporting Incorrect Datagram Headers
(12/0) Parameter-Problem
(12/1) Option Missing
(12/2) No Room for Option
Clock Synchronization and Transit Time Estimation
(13/0) Timestamp-Request
(14/0) Timestamp-Reply
Obtaining a Network Address (RARP Alternative)
(15/0) Information-Request
(16/0) Information-Reply
Obtaining a Subnet Mask [RFC 950]
(17/0) Address Mask-Request
(18/0) Address Mask-Reply
Other
(30/0) Traceroute
(31/0) Conversion-Error
(32/0) Mobile-Redirect
Ref: [RFC 792] [RFC 896] [RFC 950] [RFC 1016]
www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_5_3/cofigide/qos.htm#19774
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