CompTIA XK0-006 Online Practice Questions and Exam Preparation

CompTIA XK0-006 Online Questions & Answers

• Question 61:

  An administrator has generated an RSA SSH key pair to log in to a remote server. After copying the public key and attempting to log in, the administrator sees the following message:

  [email protected]: Permission denied (publickey,password)

  After seeing the message, the administrator attempts to connect using ssh -v [email protected] and notices the following debug output:

  debug1: send_pubkey_test: no mutual signature algorithm Which of the following actions should the administrator take first to remediate this issue?

  A. Issue systemctl restart sshd on the local server.
  B. Create a new key pair by running ssh-keygen -t ecdsa.
  C. Set PermitRootLogin yes in the /etc/ssh/sshd_config file.
  D. Update permissions on the /home/admin/.ssh directory to 700 on the remote server.
  B. Create a new key pair by running ssh-keygen -t ecdsa.

• Question 62:

  A Linux administrator is configuring Apache on a system and needs to allow the service to start after every startup.

  Which of the following commands will allow the Linux administrator to accomplish this task while starting the service at the same time?

  A. systemctl mask --state=active httpd
  B. systemctl start --runtime boot httpd
  C. systemctl set-property restart httpd
  D. systemctl enable --now httpd
  D. systemctl enable --now httpd

• Question 63:

  Which of the following can reduce the attack surface area in relation to Linux hardening?

  A. Customizing the log-in banner
  B. Reducing the number of directories created
  C. Extending the SSH startup timeout period
  D. Enforcing password strength and complexity
  D. Enforcing password strength and complexity

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  Explanation

  Comprehensive and Detailed Explanation From Exact Extract:

  Reducing the attack surface area in Linux hardening refers to limiting possible points of unauthorized access. According to the CompTIA Linux+ Official Study Guide (Exam XK0-006), enforcing strong password policies is a critical aspect of security hardening. This practice ensures that user accounts are protected by passwords that are difficult to guess or crack, thus minimizing the risk of successful brute-force attacks. Implementing password complexity requirements (such as minimum length, use of uppercase, lowercase, numbers, and special characters) directly addresses one of the primary vectors for unauthorized access.

  Other options do not have a direct impact on reducing the attack surface:

  A. Customizing the log-in banner serves as a legal notification and does not affect system vulnerabilities.

  B. Reducing the number of directories created is not related to hardening or access control.

  C. Extending the SSH startup timeout period may give attackers more time to attempt a connection and does not increase security.

  CompTIA Linux+ Study Guide: Exam XK0-006, Sybex, Chapter 11: "Securing the System", Section:"Implementing Password Policies" CompTIA Linux+ XK0-006 Exam Objectives, Domain 3.0: Security

• Question 64:

  A Linux engineer is removing a previously created firewall rule.

  Which of the following commands will help the administrator accomplish this task?

  A. ufw delete 80/tcp
  B. ufw delete deny 80/tcp
  C. ufw delete 80/tcp deny
  D. delete7!
  B. ufw delete deny 80/tcp

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  Explanation

  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

• Question 65:

  A technician wants to temporarily use a Linux virtual machine as a router for the network segment 10.10.204.0 /24. Which of the following commands should the technician issue? (Select three).

  A. echo "1" > /proc/sys/net/ipv4/ip_forward
  B. iptables -A FORWARD -j ACCEPT
  C. iptables -A PREROUTING -j ACCEPT
  D. iptables -t nat -s 10.10.204.0/24 -p tcp -A PREROUTING -j MASQUERADE
  E. echo "0" > /proc/sys/net/ipv4/ip_forward
  F. echo "1" > /proc/net/tcp
  G. iptables -t nat -s 10.10.204.0/24 -A POSTROUTING -j MASQUERADE
  H. iptables -t nat -A PREROUTING -j MASQUERADE
  A. echo "1" > /proc/sys/net/ipv4/ip_forward
  B. iptables -A FORWARD -j ACCEPT
  G. iptables -t nat -s 10.10.204.0/24 -A POSTROUTING -j MASQUERADE

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  Explanation

  Comprehensive and Detailed Explanation From Exact Extract:

  To temporarily configure a Linux virtual machine as a router, the technician must enable IP forwarding and set up iptables rules to allow and masquerade traffic:

  A. echo "1" > /proc/sys/net/ipv4/ip_forward: Enables IPv4 forwarding in the Linux kernel, allowing the VM to forward packets between interfaces.

  B. iptables -A FORWARD -j ACCEPT: Adds a rule to the iptables firewall to accept all forwarded packets (allows traffic to be routed).

  G. iptables -t nat -s 10.10.204.0/24 -A POSTROUTING -j MASQUERADE: Sets up network address translation (NAT) for outgoing packets from the 10.10.204.0/24 subnet, masquerading them as if they are coming from the VM's external IP. Other options:

  C. and

  H. are not relevant for routing/NAT in this context (PREROUTING is generally used for DNAT, not for standard source NAT).

  D. is syntactically incorrect and mixes PREROUTING with MASQUERADE, which is not the proper combination for SNAT.

  E. disables forwarding.

  F. is not related to IP forwarding.

  CompTIA Linux+ Study Guide: Exam XK0-006, Sybex, Chapter 9: "Networking", Section: "Configuring Linux as a Router" CompTIA Linux+ XK0-006 Objectives: Domain 2.0 - Networking Official CompTIA Linux+ Cert Guide, Chapter 12: "Firewall and NAT configuration"

• Question 66:

  A Linux administrator receives a ticket stating that end users are unable to access the company's internal cloud server. The administrator executes the following command:

  ping usl.com

  Result:

  ping: cannot resolve usl.com: Unknown Host

  Which of the following files needs to be modified to allow end users to access usl.com?

  A. /etc/resolv.conf
  B. /etc/interfaces
  C. /etc/hosts.allow
  D. /etc/hostname
  A. /etc/resolv.conf

• Question 67:

  An administrator wants to copy files from /opt/tools to the home directory at /home/admin.

  Which of the following should the administrator run?

  A. mkdir -p /home/admin/tools
  B. cp -R /opt/tools ~
  C. cd /opt/tools; rsync /home/admin
  D. scp /opt/tools localhost:/
  B. cp -R /opt/tools ~

• Question 68:

  An administrator wants to search a file named myFile and look for all occurrences of strings containing at least five characters , where characters two and five are i , but character three is not b .

  Which of the following commands should the administrator execute to get the intended result?

  A. grep .a*^b-.a myFile
  B. grep .a., [a] myFile
  C. grepa^b*a myFile
  D. grep .i[^b].i myFile
  D. grep .i[^b].i myFile

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  Explanation

  Pattern matching using regular expressions is a key troubleshooting and text-processing skill covered in CompTIA Linux+ V8. The grep command, combined with regular expressions, allows administrators to search for complex string patterns within files.

  The requirement specifies:

  The string must contain at least five characters Character 2 must be i Character 3 must not be b Character 5 must be i

  To meet these conditions, the correct regular expression structure is:

  . # any character (position 1)

  i # literal i (position 2)

  [^b] # any character except b (position 3)

  . # any character (position 4)

  i # literal i (position 5)

  This results in the expression:

  i[^b].i

  Option D , grep .i[^b].i myFile, correctly implements this logic. It ensures positional matching and excludes unwanted characters using a negated character class ([^b]), which is explicitly covered in Linux+ V8 regular expression objectives.

  The other options contain invalid or malformed regular expressions and do not meet the positional or exclusion requirements. Linux+ V8 emphasizes understanding anchors, character classes, and position-based matching when troubleshooting log files or configuration data.

• Question 69:

  Which of the following is a protocol for accessing distributed directory services containing a hierarchy of users, groups, machines, and organizational units?

  A. SMB
  B. TLS
  C. LDAP
  D. KRB-5
  C. LDAP

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  Explanation

  Directory services are a key part of enterprise Linux environments and are covered under the Security domain in Linux+ V8. The Lightweight Directory Access Protocol (LDAP) is specifically designed to access and manage distributed directory information.

  LDAP directories store structured, hierarchical data such as users, groups, computers, and organizational units. Linux systems commonly use LDAP for centralized authentication, authorization, and identity management. LDAP is also the foundation for services like Active Directory and FreeIPA.

  The other options are incorrect. SMB is a file and printer sharing protocol. TLS is an encryption protocol used to secure communications. Kerberos (KRB-5) is an authentication protocol often used alongside LDAP but does not store directory information itself.

  Linux+ V8 documentation highlights LDAP as the primary protocol for directory-based identity services.

• Question 70:

  Which of the following is a characteristic of Python 3?

  A. It is closed source.
  B. It is extensible through modules.
  C. It is fully backwards compatible.
  D. It is binary compatible with Java.
  B. It is extensible through modules.

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  Explanation

  Python 3 characteristics are part of Linux+ V8 scripting objectives. One of Python's most important features is its modular and extensible architecture .

  Option B is correct because Python 3 supports extensibility through modules and packages. Python includes a large standard library and allows developers to extend functionality using third-party modules or custom code. This makes Python highly adaptable for automation, system management, and DevOps tasks.

  The other options are incorrect. Python is open source, not closed source. Python 3 is not fully backwards compatible with Python 2, which is a major distinction emphasized in Linux+ V8. Python is also not binary compatible with Java.

  Linux+ V8 documentation highlights Python's extensibility as a key reason it is widely used in Linux automation.