RHCSA case studies

RHCSA · Put your knowledge to work in context.

The Red Hat Certified System Administrator (RHCSA) is a credential awarded after passing the Red Hat Certified System Administrator exam, EX200, a hands-on, practical exam in which candidates perform real-world system administration tasks rather than answer multiple-choice items. Red Hat states that this exam is based on Red Hat Enterprise Linux 10, and that the skills tested are the foundation for system administration across all Red Hat products; configurations must persist after reboot without intervention, and no internet access or hard copy or electronic documentation is permitted during the exam. The RHCSA case studies are 5 cases and about 3,823 words.

Growing an XFS Volume After a Hypervisor Disk Expansion

A RHEL 9 virtual machine hosts an application that writes to /var/log/app, a single XFS filesystem on logical volume /dev/vgdata/lvapp (4.0 GB). The volume group vgdata has exactly one physical volume: the whole disk /dev/vdb, 20 GB, with no partition table.

725 words, about 4 min 2

Shared Group Directory: umask, Stale Group Membership, and Default ACLs

A shared project directory /srv/collab is owned by root:devteam with mode 2775. alice and bob are both members of devteam as a supplementary group; carol was added to devteam at 09:00 today.

777 words, about 4 min 3

A Backup Script That Behaves Differently Under Cron

/usr/local/bin/nightly-backup.sh runs from root's crontab as 0 2 /usr/local/bin/nightly-backup.sh . The script tars /home into /backup/home-$(date +%F).tar.gz and then calls notify-admin , a small wrapper installed in /usr/local/bin that sends mail through a local relay.

789 words, about 4 min 4

Two NICs, a Lost Static Address, and a Firewall Rule That Vanishes

A RHEL 9 server has two interfaces. ens3 is the management NIC, gets DHCP from 192.168.122.1/24 and must keep the default route.

736 words, about 4 min 5

SELinux Denials on a Web Application Moved to Port 9090

A RHEL 9 web server runs Apache httpd in enforcing mode. The inventory application's content lives in /srv/inventory/www, uploads are written by httpd into /srv/inventory/data (mode 2775, group apache), and httpd was configured to Listen 9090 .

796 words, about 4 min