connect descriptor

A specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.

The destination service is indicated by using its service name for the Oracle Database or its Oracle system identifier (SID) for Oracle release 11.1 databases. The network route provides, at a minimum, the location of the listener through use of a network address.

connect identifier

A name, net service name, or service name that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a connect identifier in a connect string for the service to which they want to connect, for example:

SQL> CONNECT user_name@connect_identifier
Enter password: password

default domain

The network domain within which most client requests take place. It can be the domain where the client resides, or a domain from which the client often requests network services. The default domain is also the client configuration parameter that determines what domain to append to unqualified network name requests. A name request is unqualified if it does not have a "." character within it.

easy connect naming

A naming method that allows clients to connect to a database server without any configuration. Clients use a simple TCP/IP address, which consists of a host name and optional port number, service name, and instance name:

SQL>CONNECT user_name@host[:port][/service_name][/instance_name]
Enter password: password

external procedures

Procedure or function written in the C programming language and stored in a shared library. An Oracle server can call external procedures or functions using PL/SQL routines. For Oracle Database to connect to external procedures, the server must be configured with a net service name and the listener must be configured with protocol address and service information.

global database name

The full database name that uniquely distinguishes it from any other database in your network domain.

For example:

where sales is the name you want to call your database and is the network domain in which the database is located.

installation type

A predefined component set that automatically selects which components to install. See "Oracle Client Installation Types" for a list of installation types available with each top-level component.

Interprocess Communication (IPC)

A protocol that client applications use that resides on the same node as the listener to communicate with the database. IPC can provide a faster local connection than TCP/IP.

ldap.ora file

A file created by the Oracle Net Configuration Assistant that contains the following directory access information:

  • Type of directory

  • Location of directory

  • Default administrative context the client or server uses to look up or configure connect identifiers for connections to database services

The ldap.ora file resides in $ORACLE_BASE/network/admin.


A process that resides on the server and whose responsibility is to listen for incoming client connection requests and manage the traffic to the server.

When a client requests a network session with a database server, a listener receives the actual request. If the client information matches the listener information, then the listener grants a connection to the database server.

listener.ora file

A configuration file for the listener that identifies the:

  • Listener name

  • Protocol addresses on which it is accepting connection requests

  • Services for which it is listening

The listener.ora file resides in the $ORACLE_HOME/network/admin directory.

An Oracle Database 11g Release 1 (11.1) does not require identification of the database service because of service registration. However, static service configuration is required for an Oracle Database 11g Release 1 (11.1) if you plan to use Oracle Enterprise Manager.

local naming

A naming method that resolves a net service name into a connect descriptor. This name is configured and stored in the tnsnames.ora file on each individual client.

manual undo management mode

A mode of the database in which undo blocks are stored in user-managed rollback segments.

naming method

A resolution method used by a client application to resolve a connect identifier to a network address when attempting to connect to a database service. Oracle Net Services supports the following naming methods:

  • Local naming

  • Directory naming

  • Host naming

  • External naming

net service name

A simple name for a service that resolves to a connect descriptor. Users initiate a connect request by passing a user name and password along with a net service name in a connect string for the service to which they want to connect:

SQL> CONNECT user_name@net_service_name
Enter password: password

Depending on your needs, net service names can be stored in a variety of places, including:

  • Local configuration file, tnsnames.ora, on each client

  • Directory server

  • External naming service, such as Network Information Service (NIS) or Cell Directory Service (CDS)


Acronym for operating system specific. The initialization file parameter OS_AUTHENT_PREFIX enables users to specify a prefix that Oracle uses to authenticate users attempting to connect to the database. Oracle concatenates the value of this parameter to the beginning of the user's operating system account name and password. When a connection request is attempted, Oracle compares the prefixed user name with Oracle user names in the database.

The default value of this parameter is "" (a null string), thereby eliminating the addition of any prefix to operating system account names. In earlier releases, OPS$ was the default setting.

Oracle Context

The root of a directory subtree with a relative distinguished name of cn=OracleContext, under which all Oracle software information is kept. There may be one (or more than one) Oracle Context in a directory. An Oracle Context can be associated with a directory naming context.

The Oracle Context can contain the following Oracle entries:

  • Connect identifiers for use with Oracle Net Services directory naming to make database connections

  • Enterprise user security for use with Oracle Advanced Security


ORACLE_BASE is the root of the Oracle Database directory tree. The Oracle Base directory is the top level directory that you can use to install the various oracle software products. You can use the same Oracle base directory for more than one installation. For example, /u01/app/oracle is an Oracle base directory created by the oracle user.


Corresponds to the environment in which Oracle Database products run. If you install an OFA-compliant database, using Oracle Universal Installer defaults, Oracle home (known as $ORACLE_HOME in this guide) is located beneath $ORACLE_BASE. The default Oracle home is db_n where n is the Oracle home number. It contains subdirectories for Oracle Database software executables and network files. See also Oracle home.

Oracle home

The directory path in which to install Oracle components (for example, /u01/app/oracle/product/11.1.0/db_n). You are prompted to enter an Oracle home in the Path field of the Specify File Locations window. See also ORACLE_HOME, Oracle home name.

Oracle home name

The name of the current Oracle home, for example, Db_1. Each Oracle home has a home name that distinguishes it from all other Oracle homes on your computer. During installation, you are prompted to enter an Oracle home name in the Name field on the Specify File Locations window.

Oracle schema

A set of rules that determine what can be stored in an LDAP-compliant directory server. Oracle has its own schema that is applied to many types of Oracle entries, including Oracle Net Services entries. The Oracle schema for Oracle Net Services entries includes the attributes the entries may contain.

Oracle Net foundation layer

A networking communication layer that establishes and maintains the connection between the client application and server, and exchanging messages between them.

protocol address

An address that identifies the network address of a network object.

When a connection is made, the client and the receiver of the request, such as the listener, or Oracle Connection Manager, are configured with identical protocol addresses. The client uses this address to send the connection request to a particular network object location, and the recipient "listens" for requests on this address. It is important to install the same protocols for the client and the connection recipient, and to configure the same addresses.

raw partitions

Portions of a physical disk that are accessed at the lowest possible disk (block) level.

redo log files

Files that contain a record of all changes made to data in the database buffer cache. If an instance failure occurs, then an administrator can use the redo log files to recover the modified data that was in memory.


A set of tables located in any Oracle database accessible to the Oracle Management Server. Oracle Management Server uses a repository to store all system data and application data, information about the state of managed nodes distributed throughout the environment, and information about the separately licensable management packs.

service registration

A feature by which the PMON process (an instance background process) automatically registers information with a listener. Because this information is registered with the listener, the listener.ora file does not need to be configured with this static information.

Service registration provides the listener with the following information:

  • Service name(s) for each running instance of the database

  • Instance name(s) of the database

  • Service handlers (dispatchers and dedicated servers) available for each instance

    This allows the listener to direct a client's request appropriately.

  • Dispatcher, instance, and node load information

    This allows the listener to determine which dispatcher can best handle a client connection's request. If all dispatchers are blocked, the listener can spawn a dedicated server for the connection.

This information allows the listener to determine how best to service a client connection request.


The Oracle system identifier that distinguishes the database from all other databases on your computer. The SID automatically defaults to the database name portion of the global database name (sales in the example until you reach eight characters or enter a period. You can accept or change the default value.

sqlnet.ora file

A configuration file for the client or server that specifies the:

  • Client domain to append to unqualified service names or net service names

  • Order of naming methods for the client to use when resolving a name

  • Logging and tracing features to use

  • Route of connections

  • External naming parameters

  • Oracle Advanced Security parameters

The sqlnet.ora file resides in $ORACLE_HOME/network/admin.

system identifier

See SID.

tnsnames.ora file

A configuration file that contains net service names mapped to connect descriptors. This file is used for the local naming method. The tnsnames.ora file resides in $ORACLE_BASE/network/admin.

typical configuration

Oracle Universal Installer option that performs a default configuration of a connection between Oracle Client and Oracle Database. It configures the following:

When Oracle Client attempts to connect, it tries local naming first, followed by easy connect naming.

unqualified name

A net service name that does not contain a network domain.