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Oracle DBA practice questions

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Question 1Oracle Database Architecture

A session reads a block from a datafile and a second session later requests the same block. Which SGA component keeps the copy in memory so the second read avoids physical I/O?

  1. The redo log buffer
  2. The large pool
  3. The database buffer cache Correct answer.
  4. The shared pool

Explanation

The database buffer cache holds in-memory copies of data blocks read from datafiles, so a repeated request for the same block can be satisfied without another physical read. Buffers are managed on LRU chains and are written back to disk by DBWn when they become dirty.

Question 2Oracle Database Architecture

Which background process writes modified buffers from the buffer cache to the datafiles?

  1. ARCn
  2. CKPT
  3. LGWR
  4. DBWn Correct answer.

Explanation

Database Writer (DBWn) is responsible for writing dirty buffers to their corresponding datafiles, doing so asynchronously and in batches. It is not tied to the timing of a commit, which is why commits are protected by redo rather than by block writes.

Question 3Oracle Database Architecture

Which of the following best describes an Oracle instance?

  1. The set of datafiles, control files, and online redo log files that store the data
  2. The set of server processes created for each connected user session
  3. The system global area together with the background processes Correct answer.
  4. The collection of schema objects owned by a single database user

Explanation

An instance is the combination of memory structures (the SGA) and the background processes that manage the database. The physical files that store data constitute the database, and an instance mounts and opens exactly one database at a time in a non-multitenant sense.

Question 4Oracle Database Architecture

Which of the following is the smallest logical unit of storage that Oracle reads and writes?

  1. A data block Correct answer.
  2. A segment
  3. A tablespace
  4. An extent

Explanation

Logical storage is layered as data block, extent, segment, and tablespace. The data block is the finest granularity; extents are sets of contiguous blocks, segments are sets of extents, and tablespaces are containers for segments.

Question 5Oracle Database Architecture

Redo entries generated by a transaction are first written to which memory area?

  1. The database buffer cache
  2. The shared pool
  3. The redo log buffer Correct answer.
  4. The program global area

Explanation

Change vectors describing modifications are first placed in the redo log buffer in the SGA and are later flushed to the online redo log files by LGWR. The buffer is small and circular, and flushing happens at commit, on a log switch, or when the buffer fills.

Question 6Oracle Database Architecture

Which file must be readable for an instance to mount a database, and records the names and locations of datafiles and online redo logs?

  1. The alert log
  2. The password file
  3. The server parameter file
  4. The control file Correct answer.

Explanation

The control file is a small binary file that records the database structure, including datafile and redo log member names plus checkpoint and SCN information. An instance needs the control file to mount the database, so it is multiplexed for protection.

Question 7Oracle Database Architecture

Users run the same SQL text repeatedly and Oracle reuses the parsed form instead of reparsing it. Which SGA area holds that parsed representation?

  1. The redo log buffer
  2. The shared pool Correct answer.
  3. The large pool
  4. The database buffer cache

Explanation

The shared pool contains the library cache, which stores parsed SQL and PL/SQL along with their execution plans, and the data dictionary cache. When matching SQL is found in the library cache, the parse work is skipped.

Question 8Oracle Database Architecture

Which background process applies redo to roll the datafiles forward during instance recovery?

  1. PMON
  2. ARCn
  3. SMON Correct answer.
  4. DBWn

Explanation

System Monitor (SMON) performs instance recovery by applying redo to bring datafiles to the crash point, then rolls back uncommitted transactions. It also coalesces free space and cleans up temporary segments at instance startup.

Question 9Oracle Database Architecture

Which background process cleans up after a failed user process, freeing its resources and removing its entry from the instance?

  1. RECO
  2. PMON Correct answer.
  3. SMON
  4. CKPT

Explanation

Process Monitor (PMON) notices abnormally terminated user processes, releases their resources, and removes them from the instance's process table. It also helps register the instance with the listener.

Question 10Oracle Database Architecture

Which background process copies filled online redo log files to an archive destination?

  1. LGWR
  2. CKPT
  3. ARCn Correct answer.
  4. DBWn

Explanation

Archiver processes (ARCn) copy each filled online redo log group to the configured archive destinations when the database runs in ARCHIVELOG mode. These archived logs let you recover a backup by rolling forward past the point of the backup.

Question 11Oracle Database Architecture

What is the primary purpose of an undo tablespace?

  1. To cache recently read data blocks in memory
  2. To hold temporary sort segments for large queries
  3. To buffer redo entries before they reach the log files
  4. To keep undo records used for rollback and read consistency Correct answer.

Explanation

Undo records hold the before-images of changed data. They are used to roll back transactions, to recover the database, and to construct consistent read images for queries that started before a change was committed.

Question 12Oracle Database Architecture

Which memory structure is used for large allocations such as RMAN backup buffers and shared server session memory?

  1. The shared pool
  2. The database buffer cache
  3. The large pool Correct answer.
  4. The Java pool

Explanation

The large pool provides a separate area for sizable allocations that could otherwise fragment the shared pool, such as RMAN I/O buffers and shared server session memory. Isolating these allocations keeps the shared pool available for cursors and dictionary data.

Question 13Oracle Database Architecture

Which statement about the program global area is correct?

  1. A memory region shared by every session in the instance
  2. A nonshared region holding a server process's sort work areas Correct answer.
  3. A per-session cache of data blocks read from datafiles
  4. A subarea of the system global area allocated per session

Explanation

The PGA is private memory allocated to each server or background process. It contains session variables and SQL work areas such as sort and hash join areas, which can be sized automatically when PGA_AGGREGATE_TARGET is set.

Question 14Oracle Database Architecture

What is a set of extents allocated to a single database object such as a table or an index called?

  1. A segment Correct answer.
  2. A datafile
  3. A data block
  4. A tablespace

Explanation

A segment is the logical storage structure that consists of one or more extents allocated for a specific object. Each table, index, undo, and temporary object is represented by its own segment.

Question 15Oracle Database Architecture

What does CKPT do at a checkpoint?

  1. It writes every dirty buffer and then closes the datafiles
  2. It rolls back uncommitted transactions and frees their undo segments
  3. It records the checkpoint position in the control file and datafile headers Correct answer.
  4. It copies the current redo log group to the archive destination

Explanation

At a checkpoint CKPT updates the control file and each datafile header with the checkpoint position, so recovery knows where to start applying redo. DBWn does the block writing part; CKPT maintains the metadata that tracks progress.

Question 16Oracle Database Architecture

In a multitenant database, what is a pluggable database?

  1. A second copy of the root container's data dictionary and metadata
  2. A read-only snapshot of the container database root at a point in time
  3. A set of schemas and tablespaces that looks like a separate database Correct answer.
  4. An instance with its own system global area and background processes

Explanation

A PDB is a portable collection of schemas, schema objects, and non-schema objects that presents itself to applications as a self-contained database. Many PDBs share the memory and background processes of the single CDB instance.

Question 17Oracle Database Architecture

A session commits and receives confirmation. Which action makes the transaction recoverable if the instance crashes immediately afterward?

  1. CKPT recorded the commit SCN in the headers of every datafile
  2. PMON flushed the session's undo records to the undo tablespace
  3. DBWn wrote all changed blocks to the datafiles before the commit
  4. LGWR flushed the transaction's redo entries to disk before the commit Correct answer.

Explanation

Oracle uses write-ahead logging: a commit completes only after LGWR has written the transaction's redo records to the online redo log files. Recovery can therefore reapply those changes, so dirty blocks do not need to be written at commit time.

Question 18Oracle Database Architecture

What occurs when a log switch takes place in an Oracle database?

  1. The control file is backed up and the sequence resets to one
  2. LGWR switches to the next group and a checkpoint is triggered Correct answer.
  3. SMON archives the filled group and then clears its contents
  4. DBWn writes out every dirty buffer and CKPT closes the redo log

Explanation

At a log switch LGWR stops writing to the current group and begins writing to the next available group, and the switch triggers a checkpoint so that DBWn catches up on block writes. In ARCHIVELOG mode ARCn can then archive the filled group.

Question 19Oracle Database Architecture

With Automatic Segment Space Management, which mechanism tracks how much free space is available in each block of a segment?

  1. Per-block bitmaps recording free space within the segment Correct answer.
  2. The high-water mark that is recorded in the control file
  3. An extent map maintained in the data dictionary tables
  4. Free lists maintained in the header block of each segment

Explanation

Under ASSM a segment header points to bitmap blocks whose bits describe the free space in each block below the high-water mark. Inserts consult these bitmaps instead of contending on free lists, which improves concurrency for concurrent inserts.

Question 20Oracle Database Architecture

An instance is terminated with SHUTDOWN ABORT. What happens the next time the database is started?

  1. No recovery is needed; committed data is already in the datafiles
  2. The database stays in read-only mode until media recovery finishes
  3. The DBA must apply archived redo logs manually before opening
  4. SMON performs instance recovery automatically at the next startup Correct answer.

Explanation

An abort leaves the instance without a clean shutdown, so the datafiles may contain uncommitted changes and may be missing committed ones. At the next startup SMON applies redo from the online redo logs to roll forward, then rolls back uncommitted transactions before the database opens.

Question 21Create an Oracle Database Instance

You start an instance with the STARTUP NOMOUNT command. Which files does Oracle read while executing this command?

  1. The parameter file only Correct answer.
  2. The control file only
  3. The parameter file and the control file
  4. The parameter file, the control file, and the data files

Explanation

STARTUP NOMOUNT reads the parameter file to allocate the SGA and start background processes. The control file is read at the MOUNT stage and the data files at the OPEN stage, so neither is touched by NOMOUNT.

Question 22Create an Oracle Database Instance

Which statement about the server parameter file (SPFILE) is true?

  1. It is read once at instance startup and is never written by the server.
  2. It must be located in the operating-system working directory of the server process.
  3. It can be edited with a standard text editor while the instance is running.
  4. It is a binary file that only the Oracle server writes to. Correct answer.

Explanation

The SPFILE is a binary file maintained exclusively by the Oracle server; changes are made through ALTER SYSTEM or CREATE SPFILE statements. Manual editing is not supported and can corrupt the file, which by default resides in the platform-specific Oracle home directory structure.

Question 23Create an Oracle Database Instance

What does the ORACLE_SID environment variable identify?

  1. The directory in which the data files of the database are stored
  2. The name of the listener that forwards connections to the database
  3. The system identifier of the local instance to which a client connects Correct answer.
  4. The path of the Oracle software installation that runs the instance

Explanation

ORACLE_SID names the local instance and is used to locate the matching parameter file and to attach to the shared memory of that instance. The Oracle software location is identified by ORACLE_HOME, not by ORACLE_SID.

Question 24Create an Oracle Database Instance

Which description best matches the purpose of the SYSAUX tablespace?

  1. It stores the undo records that support transaction rollback.
  2. It records redo change vectors before they are written to the online redo log.
  3. It stores data for database features and components that previously required their own tablespaces. Correct answer.
  4. It holds the temporary segments used during sort operations.

Explanation

SYSAUX is the auxiliary tablespace created with the database to hold data for components such as the automatic workload repository, Oracle Text, and Oracle Spatial. Keeping this data out of SYSTEM reduces contention on the SYSTEM tablespace.

Question 25Create an Oracle Database Instance

Which account owns the data dictionary base tables and is automatically granted the SYSDBA privilege when a database is created?

  1. DBSNMP
  2. SYSTEM
  3. SYS Correct answer.
  4. OUTLN

Explanation

SYS owns the base tables of the data dictionary and is granted SYSDBA automatically at database creation. SYSTEM owns the data dictionary views and additional administrative objects but is not the owner of the base tables.

Question 26Create an Oracle Database Instance

Which tool is the Oracle-recommended graphical interface for creating a new database?

  1. SQL*Plus
  2. Oracle Net Manager
  3. Database Configuration Assistant (DBCA) Correct answer.
  4. Oracle Enterprise Manager Cloud Control

Explanation

DBCA provides a guided, graphical workflow for creating a database and can also generate and run the underlying scripts in silent mode. SQL*Plus can create a database only by running hand-written scripts.

Question 27Create an Oracle Database Instance

You execute the statement ALTER SYSTEM SET PROCESSES = 300 SCOPE = SPFILE; What is the effect of this statement?

  1. The new value is written to the parameter file and takes effect only after the instance is restarted. Correct answer.
  2. The statement fails because PROCESSES cannot be changed without recreating the database.
  3. The new value takes effect immediately for all sessions and is also written to the parameter file.
  4. The new value takes effect immediately but is lost when the instance is shut down.

Explanation

SCOPE=SPFILE records the change only in the server parameter file, so the running instance keeps its current value until the next startup. Parameters changed in this scope are not applied to the current instance.

Question 28Create an Oracle Database Instance

You must open a database so that only users holding the RESTRICTED SESSION privilege can connect to it. Which command accomplishes this?

  1. STARTUP FORCE followed by ALTER SYSTEM KILL SESSION for every connected user;
  2. ALTER DATABASE RESTRICT SESSIONS;
  3. STARTUP MOUNT followed by ALTER DATABASE OPEN RESTRICTED;
  4. STARTUP RESTRICT; Correct answer.

Explanation

STARTUP RESTRICT opens the database in restricted mode, allowing connections only for users granted the RESTRICTED SESSION privilege. Restricted mode can also be enabled later with ALTER SYSTEM ENABLE RESTRICTED SESSION.

Question 29Create an Oracle Database Instance

A database is currently open for read/write. You need to make its data available for queries only, with no modifications permitted. Which approach works?

  1. Shut down the database, start it in MOUNT state, and issue ALTER DATABASE OPEN READ ONLY; Correct answer.
  2. ALTER SYSTEM SET READ_ONLY = TRUE;
  3. STARTUP READ ONLY;
  4. ALTER DATABASE READ ONLY; issued while the database is open

Explanation

A read-only open is performed from the mounted state, so the database must first be shut down and started with STARTUP MOUNT. The ALTER DATABASE OPEN READ ONLY statement then opens the data files for queries only.

Question 30Create an Oracle Database Instance

Before you can issue a CREATE DATABASE statement, which instance state and which parameter setting are required?

  1. The instance must be in NOMOUNT state, and DB_NAME must be set in the parameter file used to start it. Correct answer.
  2. The instance must be in MOUNT state, and CONTROL_FILES must point to existing control files.
  3. The instance must be OPEN, and DB_NAME must match the name of the current database.
  4. The instance must be in NOMOUNT state, and all data files must already exist on disk.

Explanation

CREATE DATABASE is executed against a started but unmounted instance, because no control file exists yet. The instance must know the intended database name through DB_NAME in the parameter file used at NOMOUNT.

Question 31Create an Oracle Database Instance

You want Oracle to generate the names and locations of the data files, redo log files, and control files while you create a database. Which configuration supports this?

  1. Set DB_FILE_NAME_CONVERT and use relative file names in the statement.
  2. Set CONTROL_FILES to a directory path and create the tablespaces with AUTOEXTEND ON.
  3. Set DB_CREATE_FILE_DEST and omit the file name clauses in the CREATE DATABASE statement. Correct answer.
  4. Set DB_CREATE_ONLINE_LOG_DEST_n and specify full paths for all files.

Explanation

When DB_CREATE_FILE_DEST is set, Oracle Managed Files naming supplies the file names and locations for the files created during database creation. File name clauses can then be omitted from the CREATE DATABASE statement.

Question 32Create an Oracle Database Instance

You want an administrator to connect to the database remotely with the SYSDBA privilege by using a password file. Which steps are required?

  1. Set REMOTE_LOGIN_PASSWORDFILE to NONE and add the administrator to the OSDBA operating system group.
  2. Create the file with the orapwd utility and grant the SYSDBA privilege to the administrator. Correct answer.
  3. Insert a row for the administrator into a table in the SYSTEM schema using the ORAPWD package.
  4. Create the file with the orapwd utility, after which all remote connections are authenticated by the operating system.

Explanation

A password file created with the orapwd utility allows remote administrative authentication, and the administrator must be granted the SYSDBA privilege, which stores their credentials in that file. REMOTE_LOGIN_PASSWORDFILE must not be NONE for this to work.

Question 33Create an Oracle Database Instance

You need to raise MAXLOGFILES for an existing database. What must you do?

  1. Issue ALTER DATABASE SET MAXLOGFILES 20;
  2. Add several new redo log groups; the limit increases automatically.
  3. Recreate the control file with the larger value, or recreate the database. Correct answer.
  4. Change the value with ALTER SYSTEM and restart the instance.

Explanation

MAXLOGFILES and the related MAXLOGMEMBERS and MAXDATAFILES limits are fixed in the control file when the database is created. Raising them requires recreating the control file with the new value, or recreating the database.

Question 34Create an Oracle Database Instance

An instance has become unresponsive and you want to perform an unclean shutdown and restart it with a single command. Which command should you use?

  1. STARTUP FORCE Correct answer.
  2. STARTUP MOUNT followed by ALTER DATABASE OPEN
  3. SHUTDOWN IMMEDIATE followed by STARTUP
  4. SHUTDOWN ABORT

Explanation

STARTUP FORCE first performs a SHUTDOWN ABORT and then starts the instance again in one step. It is intended for situations where a normal or immediate shutdown is not possible.

Question 35Create an Oracle Database Instance

Which statement about the DB_BLOCK_SIZE parameter is correct?

  1. It can be changed only while the database is mounted.
  2. It can be changed with ALTER SYSTEM while the database is open.
  3. It must be a multiple of the redo log block size and can be modified at any time.
  4. It is set when the database is created and cannot be changed afterward without recreating the database. Correct answer.

Explanation

DB_BLOCK_SIZE defines the block size of the SYSTEM tablespace and is fixed when the database is created. It is not a dynamic parameter, so changing it requires creating the database again.

Question 36Create an Oracle Database Instance

Which dynamic performance view would you query to determine whether the database is running in ARCHIVELOG mode?

  1. V$DATABASE Correct answer.
  2. V$INSTANCE
  3. V$PARAMETER
  4. V$LOG

Explanation

V$DATABASE contains the LOG_MODE column, which reports whether the database is in ARCHIVELOG or NOARCHIVELOG mode. The other views report instance status, log group details, or parameter values.

Question 37Create an Oracle Database Instance

You are creating a database whose SYSTEM tablespace uses 8 KB blocks, and you also need a tablespace that uses 16 KB blocks. Which configuration is required?

  1. Set DB_16K_CACHE_SIZE and create the tablespace with the BLOCKSIZE 16K clause. Correct answer.
  2. Set DB_BLOCK_SIZE to 16K and restart the instance.
  3. Set DB_BLOCK_SIZE to 16K and create the database so that it supports two block sizes.
  4. Set DB_8K_CACHE_SIZE only and create the tablespace with default storage.

Explanation

DB_BLOCK_SIZE fixes the block size of the SYSTEM tablespace at creation, and nonstandard block sizes are supported through the corresponding DB_nK_CACHE_SIZE parameters. The tablespace must then be created with a matching BLOCKSIZE clause.

Question 38Create an Oracle Database Instance

Which statement about the DIAGNOSTIC_DEST initialization parameter is correct?

  1. It defaults to the value of ORACLE_BASE; if ORACLE_BASE is also unset, it defaults to ORACLE_HOME/rdbms/log. Correct answer.
  2. It determines the location of the alert log only, while trace files are always written to ORACLE_HOME/rdbms/log.
  3. It is reset to a null value each time the instance starts.
  4. It must be set explicitly before the instance can start.

Explanation

When DIAGNOSTIC_DEST is not set, Oracle derives it from ORACLE_BASE, and if that is also unset it falls back to ORACLE_HOME/rdbms/log. The parameter defines the base of the Automatic Diagnostic Repository, which holds the alert log, trace files, and dumps.

Question 39Create an Oracle Database Instance

Both an SPFILE and a PFILE exist in their default locations for your instance. You issue STARTUP with no PFILE clause. What happens?

  1. The instance fails to start because Oracle cannot determine which file to use.
  2. The SPFILE is used because it takes precedence over the PFILE. Correct answer.
  3. The PFILE is used because it is always read before the SPFILE.
  4. Oracle merges the two files, with SPFILE values overriding PFILE values.

Explanation

When no PFILE clause is given, the server looks for an SPFILE first and uses it if present; the PFILE is consulted only when no SPFILE is found. To force the text file, you must name it in the PFILE clause of the STARTUP command.

Question 40Create an Oracle Database Instance

In a CREATE DATABASE statement you omit the UNDO TABLESPACE clause and supply no other undo-related clause. What is the result?

  1. The CREATE DATABASE statement fails with an error.
  2. The database is created with an undo tablespace named UNDOTBS1.
  3. The database is created without an undo tablespace, and you must create and assign one afterward. Correct answer.
  4. The SYSTEM tablespace is used for undo, and no further action is needed.

Explanation

The UNDO TABLESPACE clause of CREATE DATABASE is optional; if it is omitted, no undo tablespace is created. You must then create one and make it the database undo tablespace before normal read/write activity can proceed.

Question 41Configuring the Oracle Network Environment

What is the default TCP port on which an Oracle database listener accepts client connections when no port is specified?

  1. 1630
  2. 1526
  3. 1521 Correct answer.
  4. 5500

Explanation

The listener's default listening endpoint uses TCP port 1521, and any connect descriptor or Easy Connect string that omits a port defaults to that value. Other port numbers take effect only when explicitly configured in listener.ora and referenced by the client.

Question 42Configuring the Oracle Network Environment

Which client-side configuration file typically stores net service names when the local naming method is used?

  1. sqlnet.ora
  2. tnsnames.ora Correct answer.
  3. cman.ora
  4. listener.ora

Explanation

Local naming stores connect descriptors under net service name aliases in tnsnames.ora, which the client reads when resolving a connection identifier. The file is located through TNS_ADMIN, the user's home directory, or the Oracle home network/admin directory.

Question 43Configuring the Oracle Network Environment

Which operating system command starts the default listener?

  1. sqlplus / as sysdba
  2. lsnrctl services
  3. lsnrctl start Correct answer.
  4. lsnrctl status

Explanation

The LSNRCTL utility controls the listener, and START launches it using the configuration in listener.ora. The listener then begins accepting connections and, for that instance, registering services.

Question 44Configuring the Oracle Network Environment

A client must resolve net service names using local naming first and fall back to Easy Connect naming second. Which sqlnet.ora entry accomplishes this?

  1. SQLNET.NAMING_ORDER = (TNSNAMES, EZCONNECT)
  2. NAMES.PREFERRED_METHODS = (TNSNAMES, EZCONNECT)
  3. NAMES.DIRECTORY_PATH = (TNSNAMES, EZCONNECT) Correct answer.
  4. NAMES.DEFAULT_DOMAIN = (TNSNAMES, EZCONNECT)

Explanation

NAMES.DIRECTORY_PATH lists the naming methods the client tries, in the order given, until one resolves the connect identifier. Listing TNSNAMES before EZCONNECT makes tnsnames.ora the first method consulted.

Question 45Configuring the Oracle Network Environment

A client connection attempt fails with ORA-12541: TNS:no listener. Which condition does this error indicate?

  1. The listener is running but does not recognize the requested service name
  2. Nothing is accepting connections on the host and port given in the connect descriptor Correct answer.
  3. The connect identifier could not be resolved by any configured naming method
  4. The target database instance is started but left in the MOUNT state

Explanation

ORA-12541 means the client reached the host but found no listener process on the specified port, so the TCP connection could not be established. Typical causes are a stopped listener, a wrong port, or a firewall blocking the port.

Question 46Configuring the Oracle Network Environment

Which connect string uses Easy Connect syntax to reach service orcl on host dbhost through port 1522?

  1. //dbhost:1522/orcl
  2. dbhost:1522/orcl Correct answer.
  3. dbhost/orcl:1522
  4. orcl@dbhost:1522

Explanation

Easy Connect syntax is host[:port][/service_name], so the host comes first, an optional port follows a colon, and the service name follows a slash. No tnsnames.ora entry is required for this form.

Question 47Configuring the Oracle Network Environment

An instance must register with a listener that listens on port 1525 instead of the default. Which initialization parameter should be set?

  1. LOCAL_LISTENER Correct answer.
  2. SERVICE_NAMES
  3. DISPATCHERS
  4. REMOTE_LISTENER

Explanation

LOCAL_LISTENER tells the instance which local listener address to register with when it differs from the default of port 1521 on the local host. Its value can be an address list or a net service name that resolves to the listener address.

Question 48Configuring the Oracle Network Environment

Which section of listener.ora statically registers a database instance with the listener by SID?

  1. DESCRIPTION_LIST_LISTENER
  2. ADDRESS_LIST_LISTENER
  3. SERVICE_LIST_LISTENER
  4. SID_LIST_LISTENER Correct answer.

Explanation

Static registration uses SID_LIST_<listener_name>, where each SID_DESC provides a SID_NAME, ORACLE_HOME, and optionally a GLOBAL_DBNAME. Such services appear in listener status as UNKNOWN until the instance registers dynamically.

Question 49Configuring the Oracle Network Environment

Which command changes a listener parameter, such as its logging or tracing state, at runtime without editing listener.ora?

  1. lsnrctl alter log_status off
  2. lsnrctl modify log_status off
  3. lsnrctl set log_status off Correct answer.
  4. lsnrctl update log_status off

Explanation

The LSNRCTL SET command changes a listener parameter, such as TRACE_LEVEL or LOG_STATUS, for the running listener. The change is temporary and is lost the next time the listener is started from listener.ora.

Question 50Configuring the Oracle Network Environment

After adding a new SID_DESC to listener.ora, you want the running listener to apply the change without terminating existing client connections. Which command should you use?

  1. lsnrctl register
  2. lsnrctl reload Correct answer.
  3. lsnrctl refresh
  4. lsnrctl stop and then lsnrctl start

Explanation

RELOAD makes the running listener re-read listener.ora while keeping its process and current connections intact. It is the standard way to apply configuration edits such as new static service entries.