CompTIA Updated XK0-005 Exam Questions and Answers by roscoe

The best commands to use to generate a list of rogue process names that have a TCP listener on a network interface are A. netstat -antp | grep LISTEN and B. lsof -iTCP | grep LISTEN. These commands will show the process ID (PID) and name of the processes that are listening on TCP ports, which can be used to identify any suspicious or unauthorized processes. The other commands are either not specific enough, not valid, or not relevant for this task. For example:

• C. lsof -i:22 | grep TCP will only show the processes that are listening on port 22, which is typically used for SSH, and not any other ports.
• D. netstat -a | grep TCP will show all the TCP connections, both active and listening, but not the process names or IDs.
• E. nmap -p1-65535 | grep -i tcp will scan all the TCP ports on the local host, but not show the process names or IDs.
• F. nmap -sS 0.0.0.0/0 will perform a stealth scan on the entire internet, which is not only impractical, but also illegal in some countries.

The output shows the file access control list (FACL) of the /comptia directory, which is an extension of the standard Linux permissions that allows more fine-grained control over file and directory access1. The FACL consists of two parts: the access ACL and the default ACL. The access ACL applies to the current object, while the default ACL applies to the objects created within the directory2.

The access ACL has three entries: user, group, and other. These are similar to the standard Linux permissions, but they can be specified for individual users or groups as well. The user entry shows that the owner of the directory (root) has read, write, and execute permissions (rwx). The group entry shows that the group owner of the directory (root) has read and execute permissions (r-x). The other entry shows that all other users have no permissions (—).

The default ACL has five entries: user, group, group:wheel, mask, and other. These are applied to any files or directories created within /comptia. The user entry shows that the owner of the new object will have read, write, and execute permissions (rwx). The group entry shows that the group owner of the new object will have read and execute permissions (r-x). The group:wheel entry shows that the members of the wheel group will have read, write, and execute permissions (rwx) on the new object. The mask entry shows that the maximum permissions allowed for any user or group are read, write, and execute (rwx). The other entry shows that all other users will have no permissions (—) on the new object.

Therefore, based on the FACL output, members of the wheel group can read files in /comptia, as they have read permission on both the directory and any files within it. Option B is incorrect because the sticky bit is not set on /comptia or any files within it. The sticky bit is a special permission that prevents users from deleting or renaming files that they do not own in a shared directory3. It is symbolized by a t character in the execute position of others. Option C is incorrect because other users cannot create files in /comptia, as they have no permissions on the directory or any files within it. Option D is incorrect because root is not the only user who can create files in /comptia. Any user who has write permission on the directory can create files within it, such as members of the wheel group.

The command that will permanently resolve the issue of high CPU load and average is kill -9 6295. This command will send a SIGKILL signal to the process with the PID 6295, which is the process that is consuming 99.7% of the CPU according to the top output. The SIGKILL signal will terminate the process immediately and free up the CPU resources. The kill command is used to send signals to processes by PID or name.

The other options are not correct commands for resolving this issue. The renice -n -20 6295 command will change the priority (niceness) of the process with PID 6295 to -20, which is the highest priority possible. This will make the process more CPU-intensive, not less. The renice command is used to change the priority of running processes. The pstree -p 6295 command will show a tree of processes with PID 6295 as the root. This will not affect the CPU load or average, but only display information. The pstree command is used to display a tree of processes. The iostat -cy 1 5 command will show CPU and disk I/O statistics for 5 iterations with an interval of 1 second. This will also not affect the CPU load or average, but only display information. The iostat command is used to report CPU and I/O statistics. References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 11: Troubleshooting Linux Systems; kill(1) - Linux manual page; renice(1) - Linux manual page; pstree(1) - Linux manual page; iostat(1) - Linux manual page

The command dig @10.10.10.20 example.com mx will query the DNS server to get mail server information. The dig command is a tool for querying DNS servers and displaying the results. The @ option specifies the DNS server to query, in this case 10.10.10.20. The mx option specifies the type of record to query, in this case mail exchange (MX) records, which identify the mail servers for a domain. The domain name to query is example.com. This command will show the MX records for example.com from the DNS server 10.10.10.20. This is the correct command to use to accomplish the task. The other options are incorrect because they either use the wrong syntax (@example.com 10.10.10.20 instead of @10.10.10.20 example.com), the wrong type of record (a or ptr instead of mx), or the wrong domain name (example.com ns instead of example.com mx). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 13: Managing Network Services, page 415.