SkillTestPro | CompTIA Linux+ Practice Test 10

CompTIA Linux+ Practice Test 10

CompTIA Linux+ Practice Test

1 / 10

A user reports slow SSH logins. journalctl -u sshd shows "reverse mapping" delays. Which command disables this to speed up logins?

iptables -A INPUT -p tcp --dport 22 -j ACCEPT

systemctl disable sshd

echo "GSSAPIAuthentication no" >> /etc/ssh/sshd_config

sed -i 's/DNS=yes/DNS=no/' /etc/resolv.conf

echo "UseDNS no" >> /etc/ssh/sshd_config && systemctl restart sshd

2 / 10

A server’s /etc/fstab has a typo, causing a mount failure at boot and dropping to emergency mode. Which command edits it from recovery?

nano /etc/fstab

mount -o remount,rw /etc/fstab

fsck /etc/fstab

vi /etc/fstab

systemctl edit fstab

3 / 10

A script fails with "command not found" for jq, despite being installed. which jq shows nothing. What’s the fix?

apt reinstall jq

export PATH=$PATH:/usr/local/bin

source /etc/profile

ln -s /usr/bin/jq /bin/jq

chmod +x /usr/bin/jq

4 / 10

A database crashes with "out of memory" errors. free -m shows 100MB free, but swap is disabled. Which command enables swap on /swapfile?

swapon /swapfile

mkswap /swapfile

swapoff /swapfile

mount /swapfile

chmod 600 /swapfile

5 / 10

A server’s iptables rules block port 80 after a reboot, despite iptables -A INPUT -p tcp --dport 80 -j ACCEPT. What ensures persistence?

systemctl enable iptables

iptables -P INPUT ACCEPT

echo "iptables -A INPUT -p tcp --dport 80 -j ACCEPT" > /etc/rc.local

iptables -F

iptables-save > /etc/iptables/rules.v4

6 / 10

A user’s ~/.bashrc sets an alias, but it’s unavailable in a new SSH session. What’s the likely issue, and how do you fix it?

chmod +x ~/.bashrc

Source ~/.bash_profile with source ~/.bash_profile

Add source ~/.bashrc to ~/.bash_profile

mv ~/.bashrc /etc/bashrc

export ~/.bashrc

7 / 10

After a kernel update, a server boots to a "kernel panic" error. You need to revert to the previous kernel from GRUB. Which key edits the boot entry?

8 / 10

A cron job running tar -czf /backup/data.tar.gz /data fails with "no space left on device," but df -h shows 50% free. What’s the likely fix?

tar -czf /backup/data.tar.gz --exclude=/data/tmp /data

umount /backup && mount /backup

fsck /backup

df -i /backup && rm -rf /backup/*.old

chmod 777 /backup

9 / 10

A junior admin misconfigured /etc/hosts, and now ping server1 resolves to the wrong IP. Which command verifies the resolution order?

cat /etc/resolv.conf

nslookup server1

cat /etc/nsswitch.conf

dig server1

chost server1

10 / 10

A server’s /tmp directory is full, causing application crashes. df -h shows 100% usage, but ls -l /tmp is empty. Which command reveals hidden space usage?

du -sh /tmp/

find /tmp -type f

lsof | grep /tmp

df -i /tmp

stat /tmp

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