IPv4-Cheat-Sheet - IPv4 CIDR Subnet Mask & Special IP Notes

Oct 13, 2026

IPv4 CIDR cheat sheet summarizing subnet mask, wildcard mask, and the number of addresses for prefix lengths /0 through /32. Includes notable IPv4 subnet ranges such as RFC 1918 private space, loopback, link-local, CG-NAT, and documentation prefixes. Provides a list of notable multicast addresses used by protocols like OSPF, RIP, EIGRP, and VRRP. Adds an encapsulation overhead reference table covering GRE and several tunneling/encapsulation methods.

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CategoryGeneral

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Pages1

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CIDR Subnet Mask & Wildcard Mask

Prefix Lengths (/0–/32) and Address Counts

Notable IP Subnets (RFC and Special Ranges)

Notable Multicast Addresses

Encapsulation Overhead (Protocol Bytes)

| CIDR Subnet Mask Wildcard Mask \# of Addresses | | | | | --- | --- | --- | --- | | /0 | 0.0.0.0 | [255.255.255.255](255.255.255.255) | 4,294,967,296 | | /1 | [128.0.0.0](128.0.0.0) | [127.255.255.255](127.255.255.255) | 2,147,483,648 | | /2 | [192.0.0.0](192.0.0.0). | [63.255.255.255](63.255.255.255) | 1,073,741,824 | | /3 | [224.0.0.0](224.0.0.0) | [31.255.255.255](31.255.255.255) | 536,870,912 | | /4 | [240.0.0.0](240.0.0.0) | [15.255.255.255](15.255.255.255) | 268,435,456 | | /5 | [248.0.0.0](248.0.0.0) | [7.255.255.255](7.255.255.255) | 134,217,728 | | /6 | [252.0.0.0](252.0.0.0) | [3.255.255.255](3.255.255.255) | 67,108,864 | | /7 | [254.0.0.0](254.0.0.0) | [1.255.255.255](1.255.255.255) | 33,554,432 | | /8 | [255.0.0.0](255.0.0.0) | [0.255.255.255](0.255.255.255) | 16,777,216 | | /9 | [255.128.0.0](255.128.0.0) | [0.127.255.255](0.127.255.255) | 8,388,608 | | /10 | [255.192.0.0](255.192.0.0) | [0.63.255.255](0.63.255.255) | 4,194,304 | | /11 | [255.224.0.0](255.224.0.0) | [0.31.255.255](0.31.255.255) | 2,097,152 | | /12 | [255.240.0.0](255.240.0.0) | [0.15.255.255](0.15.255.255) | 1,048,576 | | /13 | [255.248.0.0](255.248.0.0) | [0.7.255.255](0.7.255.255). | 524,288 | | /14 | [255.252.0.0](255.252.0.0) | [0.3.255.255](0.3.255.255) | 262,144 | | /15 | 255.254.0,0 | [0.1.255.255](0.1.255.255) | 131,072 | | /16 | [255.255.0.0](255.255.0.0) | [0.0.255.255](0.0.255.255) | 65,536 | | /17 | [255.255.128.0](255.255.128.0) | [0.0.127.255](0.0.127.255) | 32,768 | | /18 | [255.255.192.0](255.255.192.0) | [0.0.63.255](0.0.63.255) | 16,384 | | /19 | [255.255.224.0](255.255.224.0) | [0.0.31.255](0.0.31.255) | 8,192 | | /20 | [255.255.240.0](255.255.240.0) | [0.0.15.255](0.0.15.255) | 4,096 | | /21 | [255.255.248.0](255.255.248.0) | [0.0.7.255](0.0.7.255) | 2,048 | | /22 | [255.255.252.0](255.255.252.0) | [0.0.3.255](0.0.3.255) | 1,024 | | /23 | [255.255.254.0](255.255.254.0) | [0.0.1.255](0.0.1.255) | 512 | | /24 | [255.255.255.0](255.255.255.0) | [0.0.0.255](0.0.0.255) | 256 | | /25 | [255.255.255.128](255.255.255.128) | [0.0.0.127](0.0.0.127) | 128 | | /26 | [255.255.255.192](255.255.255.192) | [0.0.0.63](0.0.0.63) | 64 | | /27 | [255.255.255.224](255.255.255.224) | [0.0.0.31](0.0.0.31) | 32 | | /28 | [255.255.255.240](255.255.255.240) | [0.0.0.15](0.0.0.15) | 16 | | /29 | [255.255.255.248](255.255.255.248) | 0.0.0.7 | 8 | | /30 | [255.255.255.252](255.255.255.252) | 0.0.0.3 | 4 | | /31 | [255.255.255.254](255.255.255.254) | 0.0.0.1 | 2 | | /32 | [255.255.255.255](255.255.255.255) | 0.0.0.0 | 1 | | Notable IP Subnets | | | --- | --- | | Note | IP Range | | RFC 1918 | [10.0.0.0/8](10.0.0.0/8) | | RFC 1918 | 172.16.0.0/12 | | RFC 1918 | [192.168.0.0/16](192.168.0.0/16) | | Loopback | [127.0.0.0/8](127.0.0.0/8) | | Link Local | [169.254.0.0/16](169.254.0.0/16) | | CG-NAT | [100.64.0.0/10](100.64.0.0/10) | | Documentation | [192.0.2.0/24](192.0.2.0/24) | | Documentation | [198.51.100.0/24](198.51.100.0/24) | | Documentation | [203.0.113.0/24](203.0.113.0/24) | | Notable Multicast Addresses | | | --- | --- | | OSPF All Routers | [224.0.0.5](224.0.0.5) | | OSPF Designated | [224.0.0.6](224.0.0.6) | | RIP 2 Routers | [224.0.0.9](224.0.0.9) | | EIGRP Routers | [224.0.0.10](224.0.0.10) | | VRRP | [224.0.0.18](224.0.0.18) | | HSRP / GLBP | [224.0.0.102](224.0.0.102) | | Encapsulation Overhead | | | --- | --- | | Protocol | Bytes | | GRE | 24 | | 6 in 4 | 20 | | 4 in 6 | 40 | | IP-IP | 20 | | MPLS (per label in stack) | 4 | | 802.1Q | 4 | | Q in Q | 8 | | VXLAN | 50 | | OTV | 42 | | LISP (IPv4) | 36 | | LISP (IPv6) | 56 | | NVGRE | 42 | Connectivity Specialists Dedicated Internet-IP Transit SD-WAN – SASE – SD Internet Private WAN – Wavelength- Dark Fiber SIP Trunks – PSTN Replacement Colocation [connect@fullspansolutions.com](connect@fullspansolutions.com) [www.fullspansolutions.com](www.fullspansolutions.com)

FAQs

How does the document map CIDR prefix lengths to subnet masks and wildcard masks?

For each CIDR prefix length from /0 to /32, it lists the corresponding subnet mask and wildcard mask along with the number of addresses in that range.

Which IPv4 ranges are highlighted as notable subnets?

It highlights RFC 1918 private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), loopback (127.0.0.0/8), link-local (169.254.0.0/16), CG-NAT (100.64.0.0/10), and documentation ranges (192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24).

What encapsulation overhead values are provided?

It provides a table of protocol encapsulation overheads in bytes, including GRE, 6 in 4, 4 in 6, IP-IP, MPLS per label, 802.1Q, Q in Q, VXLAN, OTV, LISP (IPv4/IPv6), and NVGRE.

Oct 13, 2026

Upload by River Wang