This document uses the following terms:
cryptographic hash function: A function that maps an input of any length to a short output bit string of fixed length, such that finding an input that maps to a particular bit string of the correct output length, or even finding two inputs that map to the same output bit string, is computationally infeasible. For more information, see [SCHNEIER] chapters 2 and 18.
Dynamic Host Configuration Protocol (DHCP): A protocol that provides a framework for passing configuration information to hosts on a TCP/IP network, as described in [RFC2131].
hash function: A function that takes an arbitrary amount of data and produces a fixed-length result (a "hash") that depends only on the input data. A hash function is sometimes called a message digest or a digital fingerprint.
host byte order: The order in which the bytes of a multiple-byte number are transmitted or received by a host computer. The order of the bytes is dependent on the host computer's processor and can be either most significant byte first (in big-endian storage) or least significant byte first (in little-endian storage).
maximum client lead time (MCLT): The maximum amount of time, in seconds, that one server can extend a lease for a client beyond the lease time known by the partner server.
network byte order: The order in which the bytes of a multiple-byte number are transmitted on a network, most significant byte first (in big-endian storage). This may or may not match the order in which numbers are normally stored in memory for a particular processor.
partner server: In a DHCPv4 server failover relationship, the partner server is a peer DHCPv4 server. For a primary server, the partner server is the secondary server configured in the failover relationship; for a secondary server, the partner server is the primary server configured in the failover relationship.
primary server: In a DHCPv4 server failover configuration, the primary server in the failover relationship is the first server that is used when an attempt is made by a DHCP client to obtain an IP address and options. A server is primary in the context of a subnet. However, a primary server for a given subnet can also be a secondary server for another subnet.
secondary server: In a DHCPv4 server failover configuration, the secondary server in the failover relationship is the server that is used to provide DHCP service when it is unavailable from the primary DHCP server (service might be unavailable because the primary server is down or unreachable). A server is secondary in the context of a subnet. However, a secondary server for a given subnet can also be a primary server for another subnet.
Unicode: A character encoding standard developed by the Unicode Consortium that represents almost all of the written languages of the world. The Unicode standard [UNICODE5.0.0/2007] provides three forms (UTF-8, UTF-16, and UTF-32) and seven schemes (UTF-8, UTF-16, UTF-16 BE, UTF-16 LE, UTF-32, UTF-32 LE, and UTF-32 BE).
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.