Free Practice Questions for the IBM Certified Specialist S2000-025 Exam (2026 Updated)

The exportfs command maintains the list of directories that the NFS server exports. Running exportfs -a exports every directory listed in /etc/exports, which loads the new definitions into the running NFS subsystem without a restart.

Technical Deep Dive: The kernel export list can be reviewed afterwards with exportfs (no flags) or showmount -e < server > ; exportfs -u < dir > unexports a directory and exportfs -i -o < options > < dir > exports it temporarily without editing the file. On AIX, mknfsexp or smitty mknfsexp adds the entry to /etc/exports and exports it in one step. The NFS daemons (nfsd, rpc.mountd, rpc.lockd) must be active, which can be checked with lssrc -g nfs. showmount displays exports and clients, nfsstat reports statistics, and mount attaches a file system on the client side.

Raising the nice value of a running process lowers its scheduling priority. The renice command changes the nice value of an existing process identified by its PID, so renice +10 1234 makes the process less favoured by the scheduler while it keeps running.

Technical Deep Dive: AIX nice values range from 0 to 39 with a default of 20, and a higher value means a lower priority. The renice command acts on processes that already exist, using renice -n 10 -p 1234 in the flag syntax, whereas nice only starts a new command at an adjusted priority and does not take a PID. Only root can lower a nice value to raise priority. Check the effect with ps -o pid,ni,pri,pcpu,comm -p 1234. SIGTERM asks the process to terminate, so it does not meet the requirement, and SIGFREEZE is a system-internal signal used by operations such as live update and suspend, not a CPU control. For long-term control, use WLM or process limits.

The /etc/resolv.conf file holds the DNS resolver configuration. Its nameserver entries identify the DNS servers, and the resolver queries them in the order in which they are listed (up to three nameserver entries are used). It also contains the domain and search directives.

Technical Deep Dive: A minimal file looks like: nameserver 10.1.1.10, nameserver 10.1.1.11, domain example.com. It can be created with smitty resolv.conf or namerslv -a -i < ip > , and tested with nslookup or host. The order in which the system consults local files versus DNS is a separate setting in /etc/netsvc.conf (for example hosts=local,bind4), which chooses the resolution method rather than the name servers. /etc/hosts is the static local table, and /etc/rc.tcpip starts the TCP/IP daemons at boot.

The mkitab command adds a record to /etc/inittab. The record uses the format Identifier:RunLevel:Action:Command, so myservice:2:once:/usr/bin/myservice defines a record for run level 2 whose command is started once when init enters that run level.

Technical Deep Dive: Use mkitab -i < existing_id > "..." to insert the new record after a specific entry, lsitab -a to list records, chitab to change an existing record, and rmitab myservice to remove it. Never edit the file with a redirect: the first option would overwrite the whole inittab with a single line and prevent the system from booting normally. rcupdate is not an AIX command, and chitab modifies an existing record rather than adding one. The action field can be once, wait, respawn, boot, bootwait and others; respawn restarts the command if it exits. For application services, an SRC subsystem or a start script under /etc/rc.d is often preferred over inittab.

File ownership is stored in the file system as a numeric user ID (UID). The ls -l command translates that number into a user name by looking it up in the user database. If no account with that UID exists any longer, the lookup fails and ls prints the number instead, which is the normal result when a user is removed but their files are left behind.

Technical Deep Dive: Find orphaned files with find /home -xdev -nouser -ls (and -nogroup for groups). Resolve them by reassigning ownership with chown or archiving and deleting them according to policy. Be careful: if a new account is later created with UID 123, it will automatically own those files. Use rmuser -p < user > to remove an account and its authentication data, and remove or reassign the home directory deliberately. The ls -n option shows numeric IDs for all entries, but the numeric display here is caused by the missing account, not by the options used.

Local mail delivery depends on two things: the sendmail subsystem must be running, and sendmail must be able to resolve the system's own host name. lssrc -s sendmail shows whether the subsystem is active, and the hosts=local entry in /etc/netsvc.conf tells the resolver to use /etc/hosts when DNS is not configured, which is the standard remedy when sendmail cannot resolve local names.

Technical Deep Dive: Start sendmail if it is inoperative with startsrc -s sendmail -a "-bd -q30m" (it is normally started from /etc/rc.tcpip), and check that hostname returns a name that appears in /etc/hosts together with the local IP address. Examine queued messages with mailq and the mail facility entries in syslog. The sendmail configuration file is installed by default as /etc/mail/sendmail.cf, so its absence is not a typical post-installation fault. mailerd and the qdaemon group do not belong to the sendmail mail path (qdaemon is the print queue daemon), which excludes the other options.

The cron daemon runs recurring jobs defined in crontab files. The five time fields are minute, hour, day of month, month and day of week, so 0 5 * * 1 /usr/local/bin/report.sh runs the script at 05:00 every Monday (day of week 0 is Sunday, 1 is Monday).

Technical Deep Dive: crontab -e edits the invoking user's table, crontab -l lists it, and access is governed by /var/adm/cron/cron.allow and cron.deny. Cron jobs run with a minimal environment, so scripts should use absolute paths and set any required variables; output not redirected is mailed to the owner. The at command runs a job once, and batch runs a job once when system load permits, so neither provides a weekly schedule. Scripts in /etc/rc.d are executed at system startup and shutdown, not on a calendar schedule.

Entitled Capacity is the number of processing units that the shared-processor LPAR is guaranteed and currently entitled to receive from the shared pool. It is the value in effect now, including any change made through dynamic LPAR operations.

Technical Deep Dive: Minimum, Desired and Maximum values describe the limits and intent of the partition profile; Maximum Capacity is only the upper bound for dynamic changes, and virtual processor counts define the concurrency (how many cores the partition can run on) rather than the guaranteed physical capacity. To measure capacity actually consumed, use the interval form lparstat 2 5 and read physc (physical processors consumed) and %entc (percentage of entitlement consumed). Values of physc above the entitlement for an uncapped LPAR show that it is borrowing from the shared pool. topas -L and mpstat -s give the same view per logical processor.

The savevg -T flag creates the backup by using snapshots, which applies to JFS2 file systems only. External JFS2 snapshots are created for the file systems in the volume group, the data is backed up from the snapshot images, and the snapshots are removed when the backup completes.

Technical Deep Dive: A snapshot is a point-in-time image of a JFS2 file system, so the backup does not require the system or application to be taken offline. The snapshot logical volume typically needs about 2 to 15 percent of the file system size, so the volume group must have enough free physical partitions. The volume group must be varied on and its file systems mounted. For database workloads, application-level preparation (such as a database hot-backup or write-suspend mode) is still good practice to guarantee application consistency, but it does not require unmounting. The other choices cause downtime (unmount, reboot) or are not valid procedures.

The AIX Toolbox for Open Source Software provides the dnf_aixtoolbox.sh installation script as the recommended way to set up DNF. The script verifies that a suitable rpm.rte level is present, installs the prerequisite RPM packages that DNF depends on, and then installs DNF itself under /opt/freeware.

Technical Deep Dive: Download the script from the AIX Toolbox site on a system with network access and run it as root with sh dnf_aixtoolbox.sh. Afterwards use dnf install < package > , dnf update and dnf list installed, and confirm the package database with rpm -qa. Toolbox packages install in /opt/freeware and their libraries are found through /opt/freeware/lib, so LIBPATH changes are not the installation method. Using dnf to install its own prerequisites is circular because dnf does not exist yet, and yum is the older tool that DNF replaces.