204

You will also notice in Table 6-14 that the middle octet of the addresses is represented by an x. This designates that this same addressing scheme can be used across similar networks in the internetwork. This allows address allocation and security rules to be universally applied in the organization.

Internet Assigned Numbers Authority (IANA)

A company or organization that wants to have network hosts accessible from the Internet must have a block of public addresses assigned. The use of these public addresses is regu-lated, and the company or organization must have a block of addresses allocated to it. This is true for IPv4, IPv6, and multicast addresses.

IANA (http://www.iana.net) is the master holder of the IP addresses. The IP multicast addresses and the IPv6 addresses are obtained directly from IANA. Until the mid-1990s, all IPv4 address space was managed directly by the IANA. At that time, the IANA allocated remaining IPv4 address space to various other registries to manage for particular purposes or for regional areas. These registration companies are called Regional Internet Registries (RIR). The following are the major registries:

■   AfriNIC (African Network Information Centre): Africa Region, http://www.afrinic.net

■   APNIC (Asia Pacific Network Information Centre): Asia/Pacific Region, http://www.apnic.net

■   ARIN (American Registry for Internet Numbers): North America Region, http://www.arin.net

■   LACNIC (Regional Latin-American and Caribbean IP Address Registry): Latin America and some Caribbean Islands, http://www.lacnic.net

■   RIPE NCC (Reseaux IP Europeans): Europe, the Middle East, and Central Asia, http://www.ripe.net

Note

Several resources offer more information about RIRs and the registration process.

To learn more about IPv4 address registries allocations, refer to RFC 1466, “Guidelines for Management of IP Address Space,” (http://www.ietf.org/rfc/rfc1466.txt) and RFC 2050, “Internet Registry IP Allocation Guidelines” (http://www.ietf.org/rfc/rfc2050.txt).

The IANA provides information about IPv4 address allocation (http://www.iana.org/ipaddress/ ip-addresses.htm).

Look up IP addressing information at ARIN (http://www.arin.net/whois).