Sysadmin Cards Practice Exam — LearnCoachAssist

Question 1 Sysadmin Cards

What is SSH ProxyJump used for?

wget -c url continues an interrupted download. In Email > Catch-All, enable and specify the destination mailbox for unmatched addresses. Connecting through a jump/bastion host: ssh -J jumphost targethost or via config. FTP is unencrypted file transfer. SFTP runs over SSH (port 22) and is fully encrypted. FTPS is FTP with TLS/SSL encryption (ports 21/990).

Question 2 Sysadmin Cards

What does `ss -tulpn` show?

Listening TCP/UDP sockets with process names and PIDs. Fetches only HTTP headers (HEAD request) to check response codes and server info. A web-based hosting control panel provided by Hetzner for managing shared hosting, domains, emails, databases, and FTP accounts. tar -tzf archive.tgz.

Question 3 Sysadmin Cards

What does "Webspace" mean in konsoleH?

Maps a domain name directly to an IPv6 address. It sets default permission bits that are removed from newly created files and directories. Per-CPU statistics: user, system, iowait, idle percentages. The allocated disk space for your website files, emails, and databases.

Question 4 Sysadmin Cards

How do you trace system calls of a running process?

journalctl --since \"2025-12-01 10:00\" --until \"2025-12-01 12:00\" prints logs in that time range. strace -p PID attaches and prints syscalls (use cautiously). sar -u shows historical CPU utilization from collected data. journalctl -k prints kernel ring buffer logs.

Question 5 Sysadmin Cards

What command checks disk usage by filesystem?

find / -perm -4000 -type f 2>/dev/null lists files with the SUID bit set. df -h FTP: 21, SFTP: 22 (SSH), FTPS explicit: 21, FTPS implicit: 990. journalctl -k prints kernel ring buffer logs.

Question 6 Sysadmin Cards

What is the purpose of `anacron`?

ip link set dev eth0 mtu 9000 sets MTU to 9000 (jumbo frames). Runs missed scheduled jobs on systems that aren't always on, unlike cron which skips missed times. setfacl -d -m u:username:rwx directory sets default ACL for new files. ulimit -n 65535 sets max open files (within hard limit).

Question 7 Sysadmin Cards

How do you prune unused Docker data?

ip route add NETWORK via GATEWAY dev IFACE adds a route until reboot. Per-CPU statistics: user, system, iowait, idle percentages. Start of Authority: contains zone administrative information including primary nameserver and refresh intervals. docker system prune removes unused data and can delete stopped containers and unused images (review prompts carefully).

Question 8 Sysadmin Cards

How do you change FTP password in konsoleH?

Go to FTP > FTP Accounts and edit the account to set a new password. nmap -p- host scans all 65535 TCP ports. Navigate to Email > Spam Filter or SpamAssassin settings. Stores user account information: username, UID, GID, home directory, and login shell.

Question 9 Sysadmin Cards

How do you check DNS propagation globally?

dmidecode -t memory (requires root) shows physical memory information. Set mailbox size limits when creating or editing email accounts in Email > Email Accounts. Virtual filesystem exposing kernel tunables, same values as sysctl. Use online tools like dnschecker.org or whatsmydns.net to query multiple locations.

Question 10 Sysadmin Cards

How do you check SELinux mode quickly?

A value (0-1000) indicating likelihood of being killed by OOM Contains symbolic links to all file descriptors open by a process. Brings the interface eth0 down (disables it). getenforce prints Enforcing/Permissive/Disabled.

Question 11 Sysadmin Cards

What is `htop` useful for compared to `top`?

An interactive, colorful process viewer that allows scrolling, searching, and sorting with a tree view of processes. It stores system and application log files. Shows static hostname, icon name, chassis, machine ID, boot ID, OS, kernel, and architecture. 20 seconds

Question 12 Sysadmin Cards

How do you view kernel messages only?

journalctl -k prints kernel ring buffer logs. Stores text data for various purposes: SPF, DKIM, domain verification, custom data. swapon -s or cat /proc/swaps. Root can log in only with SSH key, not password authentication.

Question 13 Sysadmin Cards

How do you start containers from a Compose file in the background?

Use sftp then get -r remotedir, or use scp -r user@host:/path /local. Current shell resource limits (open files, max processes, stack size, etc.). docker compose up -d (or docker-compose up -d) starts services detached. systemd-run --on-active=5m command creates and runs a transient timer/service.

Question 14 Sysadmin Cards

What causes "Connection timed out" in FileZilla?

crontab -e opens the user's crontab in an editor. docker stats streams CPU, memory, and IO per container. Template directory whose contents are copied to new user home directories on creation. Firewall blocking the port, wrong hostname/port, server not running, or network issues.

Question 15 Sysadmin Cards

How do you clear the kernel ring buffer?

Lists all block devices with their partition tables, sizes, and filesystem types. Use sftp then get -r remotedir, or use scp -r user@host:/path /local. dmesg -c (root) clears and prints, or dmesg -C just clears. docker stats streams CPU, memory, and IO per container.

Question 16 Sysadmin Cards

What is the purpose of the `~/.ssh/config` file?

An interactive, colorful process viewer that allows scrolling, searching, and sorting with a tree view of processes. Stores text data for various purposes: SPF, DKIM, domain verification, custom data. ip route add NETWORK via GATEWAY dev IFACE adds a route until reboot. It allows users to define shortcuts and configuration options (like Hostname, User, Port, IdentityFile) for SSH connections.

Question 17 Sysadmin Cards

How do you count CPU cores on Linux?

nproc or grep -c ^processor /proc/cpuinfo returns the core count. xfs_growfs MOUNTPOINT (online grow only). Lists all PCI devices: network cards, graphics, storage controllers. 600 (read/write for owner only).

Question 18 Sysadmin Cards

What does a low /boot space warning indicate?

rsyslog is a traditional syslog daemon that writes logs to text files (e.g., /var/log/syslog). journald is part of systemd and stores logs in a binary format, accessible via journalctl. nice -n 10 command runs the command with a positive (lower priority) nice value. systemd-tmpfiles --create creates files/dirs, --clean removes old ones. Old kernels accumulating

Question 19 Sysadmin Cards

How do you list all sysctl parameters?

XFS filesystem geometry: block size, log size, allocation groups, features. pgrep Go to Server > Force showing hidden files to display dotfiles on remote. sysctl -a prints all kernel parameters and their current values.

Question 20 Sysadmin Cards

What is the difference between `rsyslog` and `journald`?

Sends ARP requests to discover if a host is on the local network and find its MAC. ip link set dev eth0 mtu 9000 sets MTU to 9000 (jumbo frames). rsyslog is a traditional syslog daemon that writes logs to text files (e.g., /var/log/syslog). journald is part of systemd and stores logs in a binary format, accessible via journalctl. ss -tlnp | grep -E ':21|:22' or systemctl status vsftpd proftpd.

Question 21 Sysadmin Cards

How do you list extended attributes?

It safely edits the sudoers file with syntax checking. getfattr -d filename or lsattr filename for ext filesystem attributes. docker build -t repo/name:tag . builds and tags the image. localhost for scripts on the same hosting, or a specific hostname provided in database settings.

Question 22 Sysadmin Cards

How do you show device status with nmcli?

Logs for the nginx systemd unit. Ubuntu's network configuration abstraction. Configs are YAML files in /etc/netplan/. nmcli device status shows all network devices and their states. apachectl graceful or systemctl reload apache2.

Question 23 Sysadmin Cards

What does `ip addr` show?

A web-based hosting control panel provided by Hetzner for managing shared hosting, domains, emails, databases, and FTP accounts. nice -n 10 command runs the command with a positive (lower priority) nice value. Network interfaces, IP addresses, and link state information. Requires: hard dependency, unit fails if dependency fails. Wants: soft dependency, continues if dependency fails.

Question 24 Sysadmin Cards

How do you check if OOM killer terminated a process?

atq lists scheduled at jobs with their IDs and times. journalctl -u name.service -f follows new log entries for that unit. lscpu shows architecture, cores, threads, cache, and CPU features. dmesg | grep -i "oom\|killed process" or check journal.

Question 25 Sysadmin Cards

What is `glances`?

journalctl -u name.service -f follows new log entries for that unit. dmesg -c (root) clears and prints, or dmesg -C just clears. A cross-platform monitoring tool with a web interface showing system overview. Template directory whose contents are copied to new user home directories on creation.

Question 26 Sysadmin Cards

How do you see a user's UID, GID, and group memberships?

The maximum queue length for pending TCP connections (listen backlog). id username prints numeric IDs and groups. -c create archive, -z gzip compress, -f write to file named backup.tgz. simple: process stays in foreground. forking: process forks and parent exits (traditional daemons).

Question 27 Sysadmin Cards

Where are nginx logs typically stored?

Currently logged-in users, their processes, and system load/uptime. Use ASCII mode for text files (converts line endings) or Binary mode for exact copies. Auto mode detects based on extension. It provides local static hostname-to-IP mappings before DNS lookup. /var/log/nginx/access.log and /var/log/nginx/error.log.

Question 28 Sysadmin Cards

What is `sshfs`?

nc -zv host 443 attempts a TCP connect and prints the result. FUSE filesystem that mounts a remote directory over SSH: sshfs user@host:/path /mnt. Shows the network path (hops) to a destination with round-trip times. Allows using local SSH keys on remote servers without copying them. Enable with ssh -A host.

Question 29 Sysadmin Cards

How do you temporarily set SELinux to permissive?

setenforce 0 (reverts after reboot unless config changed). stress-ng --cpu 4 --timeout 60s runs 4 CPU stress workers for 60 seconds. The time it takes for DNS changes to spread across all DNS servers worldwide (usually 24-48 hours max). getenforce prints Enforcing/Permissive/Disabled.

Question 30 Sysadmin Cards

What is the default FileZilla connection timeout?

ping -c 4 host sends 4 ICMP echo requests and reports loss/latency. Start of Authority: contains zone administrative information including primary nameserver and refresh intervals. Status of the periodic TRIM timer (usually weekly on modern distros). 20 seconds

Question 31 Sysadmin Cards

How do you configure ProxyJump in SSH config?

dpkg -l prints installed packages and their versions. Add ProxyJump jumpuser@jumphost under the target host entry in ~/.ssh/config. passwd -l user locks the password hash, preventing password logins. It configures a service to start automatically at boot.

Question 32 Sysadmin Cards

What is the difference between `apt update` and `apt upgrade`?

Navigate to Webspace > Directory Protection to set up HTTP Basic Auth for specific directories. apt update refreshes package indexes. apt upgrade installs available updates without removing packages (full upgrades use apt full-upgrade). Creates a temporary file or directory with a unique name safely (avoiding race conditions). Navigate to Domain Administration > Parked Domains or Aliases.

Question 33 Sysadmin Cards

What is an AAAA record?

swapon -s or cat /proc/swaps. Detailed memory statistics including total, free, available, buffers, cached, and swap. Lists all PCI devices: network cards, graphics, storage controllers. Maps a domain name directly to an IPv6 address.

Question 34 Sysadmin Cards

How do you flush neighbor entries for an interface?

chronyc sources lists configured time sources and their reachability. Use ASCII mode for text files (converts line endings) or Binary mode for exact copies. Auto mode detects based on extension. ip neigh flush dev IFACE removes cached neighbors on an interface. update-grub (runs grub-mkconfig) to update /boot/grub/grub.cfg.

Question 35 Sysadmin Cards

What command connects to SFTP from the terminal?

The server limit for concurrent connections from your IP has been reached. sftp user@host opens an interactive SFTP session over SSH. xfs_growfs MOUNTPOINT (online grow only). strace -p PID attaches and prints syscalls (use cautiously).

Question 36 Sysadmin Cards

Which command lists all installed Debian packages with versions?

Kept program in swap after exit for faster reload (obsolete on modern systems, only used for directories now). It provides local static hostname-to-IP mappings before DNS lookup. dpkg -l prints installed packages and their versions. Use View > Directory Comparison to highlight files that differ or are missing.

Question 37 Sysadmin Cards

What is a DNS CNAME record?

xfs_growfs MOUNTPOINT (online grow only). systemd-run --on-active=5m command creates and runs a transient timer/service. A Canonical Name record that maps one domain name (alias) to another domain name (canonical). pgrep

Question 38 Sysadmin Cards

How do you create an ext4 filesystem?

Navigate to https://konsoleh.hetzner.com and log in with your Hetzner hosting credentials. Sends ARP requests to discover if a host is on the local network and find its MAC. mkfs.ext4 /dev/sdX formats the partition with ext4. Navigate to Domain Administration > Parked Domains or Aliases.

Question 39 Sysadmin Cards

How do you obtain a certificate with certbot for nginx?

sar -u shows historical CPU utilization from collected data. certbot --nginx -d domain.com obtains and configures the certificate. Navigate to Webspace > Access Logs or Statistics > Raw Logs. ss -tlnp shows TCP listeners with process names and PIDs.

Question 40 Sysadmin Cards

What is `/etc/login.defs`?

Navigate to Databases > MySQL to create databases and database users. apt autoremove --purge removes unused kernels and dependencies. Defines default settings for user account creation: UID/GID ranges, password aging, umask. A summary of socket statistics by protocol and state.

Question 41 Sysadmin Cards

What is the difference between traceroute and tracepath?

A separate application (Windows) that provides FTP/FTPS server functionality, distinct from the FileZilla client. tracepath doesn't require root and also discovers MTU Usually a symlink to /run for backwards compatibility. A hard link points to the same inode as the original file, while a symbolic link points to a path name and can cross filesystems.

Question 42 Sysadmin Cards

What is the FileZilla message log pane?

Per-CPU statistics: user, system, iowait, idle percentages. The top pane showing connection commands, responses, and status messages for debugging. Stores user account information: username, UID, GID, home directory, and login shell. Makes the file append-only: can only be opened for appending, useful for logs.

Question 43 Sysadmin Cards

How do you set a default remote directory in FileZilla?

journalctl > logs.txt or journalctl --output=export > logs.export for binary format. dmesg -c (root) clears and prints, or dmesg -C just clears. Environment variables of the process (null-separated). In Site Manager, under Advanced tab, set the Default remote directory path.

Question 44 Sysadmin Cards

What does `ip link set dev eth0 down` do?

ss -tan state established lists established TCP sockets with addresses. lsblk -f shows devices, UUIDs, and filesystem types. Brings the interface eth0 down (disables it). crontab -e opens the user's crontab in an editor.

Question 45 Sysadmin Cards

What is the difference between ext4 and XFS?

XFS excels at large files and parallel I/O. ext4 is more versatile and can shrink. Both are production-ready. crontab -l (optionally with -u user as root). chown -R user:group /path recursively changes owner and group. getfacl filename displays the access control list.

Question 46 Sysadmin Cards

What does `tcpdump -n -i eth0 port 80` do?

Contains kernel images, initramfs, and bootloader configuration files. killall kills processes by exact name match. pkill kills processes based on name or other attributes (like regex matching or user ID). A separate application (Windows) that provides FTP/FTPS server functionality, distinct from the FileZilla client. Captures packets on interface eth0 for port 80 without resolving hostnames.

Question 47 Sysadmin Cards

What does `/proc/PID/cmdline` contain?

Exposes kernel objects: devices, drivers, modules, in a structured hierarchy. apt autoremove --purge removes unused kernels and dependencies. docker build -t repo/name:tag . builds and tags the image. The command line arguments used to start the process.

Question 48 Sysadmin Cards

How do you defragment an XFS filesystem?

Per-process statistics for CPU, memory, and I/O usage. nmap -p- host scans all 65535 TCP ports. xfs_fsr /mountpoint reorganizes fragmented files (can run online). Shows static hostname, icon name, chassis, machine ID, boot ID, OS, kernel, and architecture.

Question 49 Sysadmin Cards

What does `ip link set dev eth0 up` do?

ss -tlnp | grep -E ':21|:22' or systemctl status vsftpd proftpd. Brings the interface eth0 up (enables it). getenforce prints Enforcing/Permissive/Disabled. tcpdump -i IFACE -w capture.pcap writes packets to a pcap file.

Question 50 Sysadmin Cards

How do you convert MBR to GPT?

journalctl -b -1 shows the logs of the last boot session. gdisk /dev/sdX can convert (backup first!), or reinstall with GPT. The tendency of the kernel to move processes from physical memory to swap space (0-100, higher means more aggressive swapping). Listening TCP/UDP sockets with process names and PIDs.