Now that the IPv4 address space if fully allocated, perhaps it's time to update the comments in /etc/hosts ? Here is my attempt at a reasonably concise update:
# Assignments from RFC5735 (supersedes RFC1918) # # Allocated for use as the Internet host loopback address: # 127.0.0.0/8 # # Allocated for communication between hosts on a single link. Hosts obtain # these addresses by auto-configuration (in the absence of DHCP): # 169.254.0.0/16 # # Addresses within these blocks do not legitimately appear on the public Internet # and can be used without any coordination with IANA or an Internet registry: # 10.0.0.0/8 private networks # 172.16.0.0/12 private networks # 192.168.0.0/16 private networks # 192.0.2.0/24 documentation/examples # 198.51.100.0/24 documentation/examples # 203.0.113.0/24 documentation/examples # 198.18.0.0/15 benchmark interconnect testing # # Full assignments details are available here: # http://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.txt # More contentiously, this is an IPv6 counterpart: # Allocated for use as the Internet host loopback address: # ::1/128 # # Allocated special purpose address blocks: # fe80::/10 Link local addresses (auto-configured) # fc00::/7 Unique local address (private networks) # 2001:db8::/32 documentation/examples # 2001:2::/48 benchmark interconnect testing # # Full assignments details are available here: # http://www.iana.org/assignments/ipv6-unicast-address-assignments/ipv6-unicast -address-assignments.txt Note that I interpret the aim of these comments as an aide-memoire, rather than a tutorial on IP addressing schemes, so it's intentionally brief. /Pete
