1.1 Glossary

This document uses the following terms:

American National Standards Institute (ANSI) character set: A character set defined by a code page approved by the American National Standards Institute (ANSI). The term "ANSI" as used to signify Windows code pages is a historical reference and a misnomer that persists in the Windows community. The source of this misnomer stems from the fact that the Windows code page 1252 was originally based on an ANSI draft, which became International Organization for Standardization (ISO) Standard 8859-1 [ISO/IEC-8859-1]. In Windows, the ANSI character set can be any of the following code pages: 1252, 1250, 1251, 1253, 1254, 1255, 1256, 1257, 1258, 874, 932, 936, 949, or 950. For example, "ANSI application" is usually a reference to a non-Unicode or code-page-based application. Therefore, "ANSI character set" is often misused to refer to one of the character sets defined by a Windows code page that can be used as an active system code page; for example, character sets defined by code page 1252 or character sets defined by code page 950. Windows is now based on Unicode, so the use of ANSI character sets is strongly discouraged unless they are used to interoperate with legacy applications or legacy data.

audit log: A record of activities performed by the Dynamic Host Configuration Protocol (DHCP) server. The name of the audit log file is based on the current day of the week. For example, on Monday the name of the audit log file is DhcpSrvLog-Mon.

authentication level: A numeric value indicating the level of authentication or message protection that remote procedure call (RPC) will apply to a specific message exchange. For more information, see [C706] section 13.1.2.1 and [MS-RPCE].

Authentication Service (AS): A service that issues ticket granting tickets (TGTs), which are used for authenticating principals within the realm or domain served by the Authentication Service.

backup: The process of copying data to another storage location for safe keeping. This data can then be used to restore lost information in case of an equipment failure or catastrophic event.

client: A computer on which the remote procedure call (RPC) client is executing.

client-last-transaction-time: The time at which this server last received a DHCPv4 request from a given DHCPv4 client.

condition: A condition of a policy that specifies one of the fields in a DHCP Client request and the value that the field should contain to match the condition. The condition also contains an index that identifies the expression with which the condition is associated.

Coordinated Universal Time (UTC): A high-precision atomic time standard that approximately tracks Universal Time (UT). It is the basis for legal, civil time all over the Earth. Time zones around the world are expressed as positive and negative offsets from UTC. In this role, it is also referred to as Zulu time (Z) and Greenwich Mean Time (GMT). In these specifications, all references to UTC refer to the time at UTC-0 (or GMT).

DHCP Administrators: A security group whose members have administrative privileges to a Dynamic Host Configuration Protocol (DHCP) server. The users of this group can view as well as change the configuration, setting, and DHCP clients' lease records from the DHCP server.

DHCP client: The remote procedure call (RPC) clients that use the Dynamic Host Configuration Protocol Server Management Protocol (DHCPM) to configure, manage, and monitor the Dynamic Host Configuration Protocol (DHCP) server.

DHCP server database: A file stored in the persistent store. The database contains Dynamic Host Configuration Protocol (DHCP) server configuration and DHCP client lease record information.

DHCP server statistics: Statistics that define parameters, such as start time, uptime, number of various DHCP packets received by the DHCP server, number of scopes configured, number of total available addresses, and number of addresses used.

DHCP users: A security group whose members have read-only access to the DHCP server. The users of this group can read the configuration, settings, and the DHCP clients' lease record from the DHCP server but cannot modify it.

DHCPv4 client unique ID: The unique identifier for a DHCPv4 client that is generated by combining the subnet address, network interface type, and DHCPv4 client-identifier of the DHCP client.

DHCPv4 client-identifier: A unique identifier for a DHCPv4 client, as specified in [RFC2132] section 9.14.

DHCPv6 client-identifier: A DUID that is used to identify a DHCPv6 client.

DHCPv6 stateless client inventory: An inventory of stateless clients being serviced by the DHCPv6 server, maintained in the persistent store.

domain member (member machine): A machine that is joined to a domain by sharing a secret between the machine and the domain.

domain name: A name with a structure indicated by dots.

Domain Name System (DNS): A hierarchical, distributed database that contains mappings of domain names to various types of data, such as IP addresses. DNS enables the location of computers and services by user-friendly names, and it also enables the discovery of other information stored in the database.

DUID: A DHCP unique identifier that is used to identify DHCPv6 clients and servers, as specified in [RFC3315] section 9.

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].

Dynamic Host Configuration Protocol (DHCP) client: An Internet host using DHCP to obtain configuration parameters such as network addresses.

Dynamic Host Configuration Protocol (DHCP) server: A computer running a DHCP service that offers dynamic configuration of IP addresses and related information to DHCP-enabled clients.

endpoint: The IP address of a network interface on which the Dynamic Host Configuration Protocol (DHCP) server is listening for DHCP client requests.

exclusion range: The range of IP addresses in a scope that are not given out to DHCP clients.

expression: A construct that serves two purposes: specifies the logical operator (AND/OR) to be used between 2 conditions of a policy; and specifies the index of the expressions that are parent to it. Taken together, conditions and expressions specify policy classification criteria.

failover: A backup operation that automatically switches to a standby database, server, or network if the primary system fails or is temporarily shut down for servicing. Failover is an important fault tolerance function of mission-critical systems that rely on constant accessibility. To the user, failover automatically and transparently redirects requests from the failed or down system to the backup system that mimics the operations of the primary system.  A failover operation is always followed by a failback operation, which is the process of returning production to its original location.

failover relationship: An association between two DHCPv4 servers, for example, a primary server and a secondary server, that provides a resilient and highly available solution to DHCPv4 clients.

globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).

hotstandby mode: A DHCPv4 server failover configuration mode in which only one of the two servers in a failover relationship is designated to respond to all client requests: this first server is referred as the primary server. The second server, referred as the secondary server (the hot standby server), begins to serve clients when the first server goes down or there is loss of communication between the two.

Interface Definition Language (IDL): The International Standards Organization (ISO) standard language for specifying the interface for remote procedure calls. For more information, see [C706] section 4.

IP range: A range of IP addresses for each scope that can be assigned to a DHCP client.

lease record: An entry in the DHCP server database that defines the IP address that is leased out to a client. The record includes details about the IP address bound to the client, and also contains a collection of other configuration parameters.

load distribution ratio: A DHCPv4 failover configuration parameter that defines the percentage of the DHCPv4 client load shared between the primary server and secondary server of a failover relationship.

loadbalance mode: A DHCPv4 server failover configuration mode in which both primary server and secondary server in a failover relationship simultaneously serve DHCPv4 clients on the network, based on the configured load distribution ratio.

MADCAP lease identifier: An identifier for a Multicast Address Dynamic Client Allocation Protocol (MADCAP) lease, as specified in [RFC2730] section 2.4.

MADCAP lease record: A MADCAP lease record is an entry in the Multicast Address Dynamic Client Allocation Protocol (MADCAP) database that defines a multicast IP address that is leased out to a multicast client. The record includes details about the multicast IP address bound to the client, and also contains a collection of other configuration parameters.

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.

multicast address: A recipient that subscribes to the network address to receive packets sent using Multicast UDP. In a multicast address scenario, a packet is sent once by the sender and is delivered to all subscribers.

multicast scope: A group of IP multicast network addresses that can be distributed by the Dynamic Host Configuration Protocol (DHCP) server to other computers in the network using the Multicast Address Dynamic Client Allocation Protocol (MADCAP) [RFC2730].

named pipe: A named, one-way, or duplex pipe for communication between a pipe server and one or more pipe clients.

NetBIOS: A particular network transport that is part of the LAN Manager protocol suite. NetBIOS uses a broadcast communication style that was applicable to early segmented local area networks. A protocol family including name resolution, datagram, and connection services. For more information, see [RFC1001] and [RFC1002].

Network Access Protection (NAP): A feature of an operating system that provides a platform for system health-validated access to private networks. NAP provides a way of detecting the health state of a network client that is attempting to connect to or communicate on a network, and limiting the access of the network client until the health policy requirements have been met. NAP is implemented through quarantines and health checks, as specified in [TNC-IF-TNCCSPBSoH].

Network Data Representation (NDR): A specification that defines a mapping from Interface Definition Language (IDL) data types onto octet streams. NDR also refers to the runtime environment that implements the mapping facilities (for example, data provided to NDR). For more information, see [MS-RPCE] and [C706] section 14.

OEM: Original Equipment Manufacturer

opnum: An operation number or numeric identifier that is used to identify a specific remote procedure call (RPC) method or a method in an interface. For more information, see [C706] section 12.5.2.12 or [MS-RPCE].

option definition: Defines an option for a vendor class. The definition consists of two parts: an option ID and an option name.

option ID: A unique integer value used to identify a specific option [RFC2132].

option name: Defines the name of the option. Together, the option name and the option ID compose a unique identification of the option called an option definition.

option type: The data format type used for the value of a specific DHCP option value, as specified in [MS-DHCPM] section 2.2.1.1.10. The option definition can contain option values in various format types. Options can be of type BYTE,  WORD,  DWORD,  DWORD_DWORD,  IP Address, Unicode String,  Binary, or Encapsulated binary format.

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.

policy: A set of conditions and actions. The conditions provide a mechanism for classifying DHCP Clients. Classification is based on the conditions and expressions configured by the user as part of the policy. DHCP Client requests received by the server are evaluated as per the classification specified in the policy. The actions can have an associated IP address range and/or option values. If a DHCP Client request matches policy conditions, the client is given an IP address from the IP address range of the policy. The client will also be given options configured for the matched policy. A policy can be configured at the scope or server level. Multiple policies can be configured at both the scope and server levels.

policy IP range: An IP address range associated with a policy. Only DHCP Clients that match policy classification criteria will be leased an IP address from the policy IP range of the matched policy.

potential-expiration-time: The time (added to the MCLT) that a server in a failover relationship requires its partner server to wait (), before assuming that the given lease has expired.

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.

relay agent information option: The relay agent information option, as defined in [RFC3046]. The option ID for the relay agent information option is 82.

remote procedure call (RPC): A communication protocol used primarily between client and server. The term has three definitions that are often used interchangeably: a runtime environment providing for communication facilities between computers (the RPC runtime); a set of request-and-response message exchanges between computers (the RPC exchange); and the single message from an RPC exchange (the RPC message).  For more information, see [C706].

reservation: An IP address that is reserved on the DHCP server for assignment to a specific client based on its hardware address. A reservation is used to ensure that a specific DHCP client is always assigned the same IP address.

rogue DHCP server: A Dynamic Host Configuration Protocol (DHCP) server that is not an authorized server, as specified in [RFC2131], section 7.

RPC protocol sequence: A character string that represents a valid combination of a remote procedure call (RPC) protocol, a network layer protocol, and a transport layer protocol, as described in [C706] and [MS-RPCE].

RPC transport: The underlying network services used by the remote procedure call (RPC) runtime for communications between network nodes. For more information, see [C706] section 2.

scope: A range of IP addresses and associated configuration options that are allocated to DHCP clients in a specific subnet.

scope level policy: A policy that is specified at a particular scope (subnet) and which applies only to that scope is referred to as a scope level policy.

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.

security identifier (SID): An identifier for security principals that is used to identify an account or a group. Conceptually, the SID is composed of an account authority portion (typically a domain) and a smaller integer representing an identity relative to the account authority, termed the relative identifier (RID). The SID format is specified in [MS-DTYP] section 2.4.2; a string representation of SIDs is specified in [MS-DTYP] section 2.4.2 and [MS-AZOD] section 1.1.1.2.

server: A computer on which the remote procedure call (RPC) server is executing.

server level policy: A policy can be specified at each scope (subnet) or it can be specified global to the DHCP server. A policy which is global to the DHCP server is referred as a server-level policy and applies to all the scopes configured on the DHCP server.

subnet ID: An ID generated by the Dynamic Host Configuration Protocol (DHCP) server. The IPv4 subnet ID is generated by the DHCP server by performing the binary AND operation on the subnet IPv4 address and the IPv4 subnet mask. The IPv6 prefix ID is generated by the DHCP server by converting the least significant 64 bits of the IPv6 address to 0.

superscope: A feature of a DHCP server that allows an administrator to group multiple scopes as a single administrative entity.

transaction log: A log file that the Dynamic Host Configuration Protocol (DHCP) server generates to recover from incomplete transactions in the event of a DHCP server malfunction.

Transmission Control Protocol (TCP): A protocol used with the Internet Protocol (IP) to send data in the form of message units between computers over the Internet. TCP handles keeping track of the individual units of data (called packets) that a message is divided into for efficient routing through the Internet.

unicast: A style of resource location or a data transmission in which a client makes a request to a single party.

Unicast Address: An address that uniquely identifies a host on the network; any packets sent to the address are delivered to a single host.

Unicode string: A Unicode 8-bit string is an ordered sequence of 8-bit units, a Unicode 16-bit string is an ordered sequence of 16-bit code units, and a Unicode 32-bit string is an ordered sequence of 32-bit code units. In some cases, it could be acceptable not to terminate with a terminating null character. Unless otherwise specified, all Unicode strings follow the UTF-16LE encoding scheme with no Byte Order Mark (BOM).

universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the UUID.

user class: User defined classes which contain user specific DHCP options. A default user class is implementation dependent.

vendor class: User defined classes that contain vendor-specific DHCP options. A default vendor class is implementation defined.

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.