IPv4 CIDR Table


CIDR LengthMask# Networks# Hosts
/1128.0.0.0128 A 2,147,483,392
/2192.0.0.064 A 1,073,741,696
/3224.0.0.032 A 536,870,848
/4240.0.0.016 A 268,435,424
/5248.0.0.08 A 134,217,712
/6252.0.0.04 A 67,108,856
/7254.0.0.02 A 33,554,428
/8255.0.0.01 A 16,777,214
/9255.128.0.0128 B 8,388,352
/10255.192.0.064 B 4,194,176
/11255.224.0.032 B 2,097,088
/12255.240.0.016 B 1,048,544
/13255.248.0.08 B 524,272
/14255.252.0.04 B 262,136
/15255.254.0.02 B 131,068
/16255.255.0.01 B 65,024
/17255.255.128.0128 C 32,512
/18255.255.192.064 C 16,256
/19255.255.224.032 C 8,128
/20255.255.240.016 C 4,064
/21255.255.248.08 C 2,032
/22255.255.252.04 C 1,016
/23255.255.254.02 C 508
/24255.255.255.01 C 254
/25255.255.255.128 2 subnets 124
/26255.255.255.192 4 subnets 62
/27255.255.255.224 8 subnets 30
/28255.255.255.240 16 subnets 14
/29255.255.255.24832 subnets 6
/30255.255.255.25264 subnets 2
/31 255.255.255.254 none none
/32255.255.255.255 1/256 C1

IPv4 Wildcard Mask Table


CIDR LengthSubnet MaskWildcard Mask
/8255.0.0.00.255.255.255
/9255.128.0.00.127.255.255
/10255.192.0.00.63.255.255
/11255.224.0.00.31.255.255
/12255.240.0.00.15.255.255
/13255.248.0.00.7.255.255
/14255.252.0.00.3.255.255
/15255.254.0.00.1.255.255
/16255.255.0.00.0.255.255
/17255.255.128.00.0.127.255
/18255.255.192.00.0.63.255
/19255.255.224.00.0.31.255
/20255.255.240.00.0.15.255
/21255.255.248.00.0.7.255
/22255.255.252.00.0.3.255
/23255.255.254.00.0.1.255
/24255.255.255.00.0.0.255
/25255.255.255.1280.0.0.127
/26255.255.255.1920.0.0.63
/27255.255.255.2240.0.0.31
/28255.255.255.2400.0.0.15
/29255.255.255.2480.0.0.7
/30255.255.255.2520.0.0.3
/31255.255.255.2540.0.0.1

RFC 1918 Reserved Space


ClassStartEnd# HostsCIDR
A 10.0.0.0 10.255.255.255 16,777,216 /8
B 172.16.0.0 172.31.255.2551,048,544 /12
C 192.168.0.0 192.168.255.255 65,534 /16

Autonomnous System Numbers


NumberBitsDescriptionReference
016ReservedRFC1930
1 - 2345516Public ASN's 
2345616Reserved for AS Pool TransitionRFC6793
23457 - 6453416Public ASN's 
64000 - 6449516Reserved by IANA 
64496 - 6451116Reserved for use in documentation/sample codeRFC5398
64512 - 6553416Reserved for private use 
6553516Reserved 
65536 - 6555132Reserved for use in documentation and sample codeRFC4893, RFC5398
65552 - 13107132Reserved 
131072 - 419999999932Public 32-bit ASN's 
4200000000 - 429496729432Reserved for private useRFC6996
429496729532Reserved

Default Administrative Distance


Route SourceDefault Distance Values
Connected interface0
Static route1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route5
External Border Gateway Protocol (BGP)20
Internal EIGRP90
IGRP100
OSPF110
Intermediate System-to-Intermediate System (IS-IS)115
Routing Information Protocol (RIP)120
Exterior Gateway Protocol (EGP)140
On Demand Routing (ODR)160
External EIGRP170
Internal BGP200
Unknown*255

 

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