RHCSA
862 incident response problems that help with RHCSA prep.
먼저 읽을 가이드
추천 문제
All problems (862)
Too many open files: a systemd service hits its file descriptor limitToo many open files: a systemd service hits its file descriptor limit is a hands-on troubleshooting drill. Find the real per-process limit of a systemd service instead of the shell ulimit. resource-management needs to be checked by narrowing scope, recent change, and the curre...ReviewedLinuxBeginner15 minFreeLINUX-011A bind-address problem where the service port is open but only reachable from localhostA bind-address problem where the service port is open but only reachable from... is a hands-on troubleshooting drill. A situation where the application is up but the listen address is wrong, so external connections fail. Linux Service Operations needs to be checked by narrowin...LinuxBeginner15 minFreeLINUX-016A shell script where set -e skips even the normal cleanup stepA situation where the failure-handling intent was good, but an overly aggressive exit condition prevents even the recovery routine from running.LinuxBeginner16 minFreeLINUX-014A backup script that looks successful but actually keeps only an empty directoryCovers an incident where the backup output is empty because of a difference between the relative path and the current working directory.LinuxIntermediate18 minFreeLINUX-017Only the operations automation account fails to run a command due to a sudoers rule differenceCovers a situation where human accounts work but only the automation account is blocked on a specific command due to different permissions.LinuxIntermediate19 minFreeLINUX-008It looked like a memory leak, but it was really an orphan process that never terminatedAnalyzes a situation where a side worker outlives the main process and holds on to resources.LinuxIntermediate21 minFreeLINUX-002Narrowing a /var partition surge with du and lsofA hands-on disk analysis scenario that extends into a file-handle problem where space is not reclaimed after deletion.LinuxIntermediate24 minFreeLINUX-075pam_faillock keeps accounts blocked after LDAP recoveryDirectory authentication is healthy again, but users still cannot log in because the host-local lock records survived the upstream outage.LinuxIntermediate16 minFreeLINUX-089rsync backup over SSH stallsNetwork reachability is fine, but the batch backup never starts because the negotiated SSH crypto overlap disappeared during a hardening change.LinuxIntermediate16 minFreeLINUX-084sudo NOPASSWD rule is present but a later group rule still forces password promptsThe expected privilege rule exists, but one broader matching policy lower in the evaluation path overrides the operator's assumption about effective behavior.LinuxIntermediate13 minFreeLINUX-091Tmpfs mount survives the deploy but vanishes after rebootThe application worked during the change window, then failed after restart because the critical mount existed only as a temporary runtime action.LinuxIntermediate14 minFreeLINUX-071logrotate copytruncate races with a high-write process and drops critical linesThe rotation completes, but incident evidence is missing because copytruncate cut the file while the application was still writing heavily.LinuxIntermediate15 minFreeLINUX-086sshd Match block for a bastion subnet disables agent forwarding on one host class onlySSH works broadly, but a specific bastion path behaves differently because a later Match clause quietly changes capabilities for one source range.LinuxIntermediate15 minFreeLINUX-076tmpfiles.d recreates the runtime directory with the wrong owner after rebootPermissions look correct before restart, but the service fails after boot because tmpfiles recreated the path with ownership that no longer matches the daemon user.LinuxIntermediate15 minFreeLINUX-061journald rate limiting drops repeated kernel alerts during a packet stormThe host is noisy during the incident, but the most useful log lines never reach disk because journald suppression hides repeated bursts.LinuxIntermediate16 minFreeLINUX-066SELinux blocks the new content rootPermissions and ownership look correct, but the service still gets denied because the moved directory kept the wrong security context.LinuxIntermediate16 minFreeLINUX-094SELinux context is correct on the binary but the parent directory type still blocks traversalThe executable label looks valid, yet access fails because one parent directory retains a context that denies the path traversal required to reach the file.LinuxIntermediate16 minFreeLINUX-070SSSD cache preserves deleted group membership and sudo access lingers after offboardingThe identity source is already updated, but one host still grants privileged access because its local cache did not expire when the account changed.LinuxIntermediate17 minFreeLINUX-099Emergency reboot script runs from cron but loses access to the package manager lock namespace inside systemd-runThe fallback script exists, yet repair automation still fails because the execution environment differs from the shell where the operator tested it.LinuxIntermediate18 minFreeLINUX-051systemd-tmpfiles cleanup removes the application socket directory after rebootThe service worked before restart, but after boot its runtime socket path is missing because the tmpfiles policy cleaned the directory more aggressively than expected.LinuxIntermediate18 minFree