Basic Special-Use IPv4 Reference Table
Overview
This CSV was the first version of the special-use IPv4 list. It contains a concise summary of ranges reserved by IANA for special functions — such as loopback, link-local, multicast, and documentation blocks.
Although you now have the detailed version, this original version still serves as a clean, quick-reference index for people who want less reading and more direct answers.
What This CSV Contains
- CIDR range
- Name
- Brief descriptive notes
Useful for quick-glance reference, educational content, or side-by-side comparison charts.
Why Keep This Page?
Because users love:
- Quick lists
- Fast answers
- “Cheat sheet” style reference pages
This CSV page is perfect for learners or engineers who want the short version without the RFC-level detail.
| CIDR | Name | Detailed Notes |
|---|---|---|
| 0.0.0.0/8 | This Network Block | Used when a host does not yet know its IP. 0.0.0.0 as source = 'I don't have an IP yet'. Also used for DHCPDISCOVER and default-route representation. Never manually assigned; should not appear on routed networks. |
| 0.0.0.0/32 | Default Route | Represents 'anywhere' in routing tables. Not an assignable host address. |
| 255.255.255.255/32 | Limited Broadcast | Broadcast to local Layer 2 domain only. Never routed. Used for ARP, DHCP, discovery protocols. Should never appear on routed interfaces. |
| 10.0.0.0/8 | Private IPv4 Space | Massive internal-use block. Ideal for large enterprises, campus backbones, multi‑region networks. Routable internally, not globally. Commonly subnetted into /16, /20, /24. RFC1918. |
| 172.16.0.0/12 | Private IPv4 Space | Mid‑sized private block. Often used for VPN pools, server farms, segmentation. Easier to avoid conflicts than 192.168/16. RFC1918. |
| 192.168.0.0/16 | Private IPv4 Space | Most common home/SMB network space. Frequently used for VLANs, SOHO networks. High collision risk when merging networks (VPNs, acquisitions). RFC1918. |
| 169.254.0.0/16 | Link‑Local APIPA | Auto‑assigned when DHCP fails. Never routed. Used for local‑only communication, mDNS, device discovery. Seeing these in logs indicates DHCP problems. RFC3927. |
| 127.0.0.0/8 | Loopback Range | Entire /8 loops back to local host. Typically only 127.0.0.1 used, but all addresses are valid loopbacks. Critical for local testing & inter‑process communication. Packets should never appear on the wire. RFC1122. |
| 100.64.0.0/10 | Carrier‑Grade NAT | Used by ISPs for large scale NAT44 to preserve IPv4 space. Not for enterprise LAN use. Appearing internally indicates misconfiguration or ISP interference. RFC6598. |
| 192.0.0.0/24 | IETF Protocol Assignments | Reserved for protocol level functionality, transition mechanisms, and experimental uses. Rarely appears in enterprise networks. RFC5736. |
| 192.0.2.0/24 | TEST‑NET‑1 | Documentation & training examples. Must NOT be used in production networks. RFC5737. |
| 198.51.100.0/24 | TEST‑NET‑2 | Documentation & training examples. Safe for examples; never routed publicly. RFC5737. |
| 203.0.113.0/24 | TEST‑NET‑3 | Documentation & training examples. Used in textbooks, diagrams, labs. RFC5737. |
| 198.18.0.0/15 | Benchmarking Range | Used for performance testing of routers, firewalls, and other devices. Reserved for benchmark labs; not intended for general networking. RFC2544. |
| 224.0.0.0/4 | Multicast Range | All multicast traffic (IGMP, mDNS, routing protocols). 224.0.0.0 224.0.0.255 reserved for local‑network control. 239.0.0.0/8 for administratively scoped multicast. |
| 240.0.0.0/4 | Reserved (Future Use) | Experimental block. Not publicly routed. Historically unsupported, but modern OSes can route some of this block. Still considered reserved. |
| 192.88.99.0/24 | Deprecated 6to4 Relay | Formerly used for IPv6 transition. Deprecated and removed from global routing. Should not be used. RFC7526. |
| 192.175.48.0/24 | AS112 Sinkhole | Used for reverse‑DNS leaks and misconfigured private DNS queries. Operated by volunteer AS112 nodes to absorb misdirected traffic. |
| 233.252.0.0/14 | Documentation Multicast | TEST MULTICAST range for documentation. Never used in production multicast deployments. RFC6034. |
| 255.0.0.0/8 | Reserved | Reserved for future definition. Not assignable. Not routed. Packets from this block indicate spoofing or misconfiguration. |