CompTIA Updated XK0-005 Exam Questions and Answers by roscoe

The ufw (Uncomplicated Firewall) delete command is used to remove rules.

If the original rule was ufw deny 80/tcp, it must be deleted with:ufw delete deny 80/tcp

If the original rule was ufw deny 80/tcp, it must be deleted with:ufw delete deny 80/tcp

If the original rule was ufw deny 80/tcp, it must be deleted with:ufw delete deny 80/tcp

Why the other options are incorrect?

A. ufw delete 80/tcp → Incorrect, because delete requires specifying the action (allow or deny).

C. ufw delete 80/tcp deny → Incorrect syntax; deny must come before the port.

D. delete7! → Incorrect, this is not a valid ufw command.

References:

UFW Documentation – Ubuntu

The best command to use to transfer the local file accounts.pdf to the remote /tmp directory of the server with the IP address 10.10.10.80 is B. scp accounts.pdf user@10.10.10.80:/tmp. This command will use the secure copy protocol (scp) to copy the file from the local machine to the remote server over SSH. The command requires the username and password of the user on the remote server, as well as the full path of the destination directory.

The other commands are either incorrect or not suitable for this task. For example:

A. rsync user@10.10.10.80:/tmp accounts.pdf will try to use the rsync command to synchronize files between the local and remote machines, but it has the wrong syntax and order of arguments. The source should come before the destination, and a colon (:) should separate the remote host and path.

C. cp user@10.10.10.80:/tmp accounts.pdf will try to use the cp command to copy files, but it does not work over SSH and it has the wrong syntax and order of arguments. The source should come before the destination, and a colon (:) should separate the remote host and path.

D. ssh accounts.pdf user@10.10.10.80:/tmp will try to use the ssh command to log into the remote server, but it has the wrong syntax and arguments. The username should come before the remote host, and a file name is not a valid argument for ssh.

The best command to use to improve the latency issue is D. # echo ‘net.core.rmem max = 12500000’ >> /etc/sysctl.conf # echo ‘net.core.wmem_max = 12500000’ >> /etc/sysctl.conf # sysctl -p. This command will increase the size of the receive and send buffers for the network interface, which can improve the network performance and reduce packet loss. The sysctl command will apply the changes to the kernel parameters without rebooting the system.

The other commands are either incorrect or not suitable for this task. For example:

A. # echo ‘net.core.net_backlog = 5000000’ >> /etc/sysctl.conf # sysctl -p # systemctl daemon-reload will try to increase the backlog queue for incoming connections, but this is not relevant for the latency issue. The systemctl daemon-reload command is also unnecessary, as it only reloads the systemd configuration files, not the kernel parameters.

B. # ifdown eth0 # ip link set dev eth0 mtu 800 # ifup eth0 will try to change the maximum transmission unit (MTU) of the network interface to 800 bytes, but this is too low and may cause fragmentation and performance degradation. The default MTU for Ethernet is 1500 bytes, and it should not be changed unless there is a specific reason.

C. # systemctl stop network # ethtool -g eth0 512 # systemctl start network will try to change the ring buffer size of the network interface to 512, but this is too small and may cause packet drops and latency spikes. The default ring buffer size for Ethernet is usually 4096 or higher, and it should be increased if there is a high network traffic.

For repairing XFS filesystems, the appropriate command is xfs_repair. Since the /opt/finapp directory resides on an XFS filesystem (indicated in the mount output), xfs_repair is suitable for diagnosing and fixing corruption in XFS inodes and extent trees. Using fdisk or fsck.ext4 is not appropriate for XFS filesystems, as these commands are intended for partitioning and ext4 filesystems, respectively. Reference: CompTIA Linux+ Study Guide.