Practice Free N10-009 Exam Online Questions
Question #161
A network engineer performed a migration to a new mail server. The engineer changed the MX record, verified the change was accurate, and confirmed the new mail server was reachable via the IP address in the A record. However, users are not receiving email.
Which of the following should the engineer have done to prevent the issue from occurring?
- A . Change the email client configuration to match the MX record.
- B . Reduce the TTL record prior to the MX record change.
- C . Perform a DNS zone transfer prior to the MX record change.
- D . Update the NS record to reflect the IP address change.
Correct Answer: B
B
Explanation:
Understanding TTL (Time to Live):
TTL is a value in a DNS record that tells how long that record should be cached by DNS servers and clients. A higher TTL value means that the record will be cached longer, reducing the load on the DNS server but delaying the propagation of changes.
Impact of TTL on DNS Changes:
When an MX record change is made, it may take time for the change to propagate across all DNS servers due to the TTL setting. If the TTL is high, old DNS information might still be cached, leading to email being directed to the old server.
Best Practice Before Making DNS Changes:
To ensure that changes to DNS records propagate quickly, it is recommended to reduce the TTL value to a lower value (such as 300 seconds or 5 minutes) well in advance of making the changes. This ensures that any cached records will expire quickly, and the new records will be used sooner.
Verification of DNS Changes:
After reducing the TTL and making the change to the MX record, it is important to verify the propagation using tools like dig or nslookup.
Comparison with Other Options:
Change the email client configuration to match the MX record: Email clients generally do not need to match the MX record directly; they usually connect to a specific mail server specified in their settings.
Perform a DNS zone transfer prior to the MX record change: DNS zone transfers are used to replicate DNS records between DNS servers, but they are not related to the propagation of individual record changes.
Update the NS record to reflect the IP address change: NS records specify the DNS servers for a domain and are not related to MX record changes.
Reference: CompTIA Network+ study materials and DNS best practices.
B
Explanation:
Understanding TTL (Time to Live):
TTL is a value in a DNS record that tells how long that record should be cached by DNS servers and clients. A higher TTL value means that the record will be cached longer, reducing the load on the DNS server but delaying the propagation of changes.
Impact of TTL on DNS Changes:
When an MX record change is made, it may take time for the change to propagate across all DNS servers due to the TTL setting. If the TTL is high, old DNS information might still be cached, leading to email being directed to the old server.
Best Practice Before Making DNS Changes:
To ensure that changes to DNS records propagate quickly, it is recommended to reduce the TTL value to a lower value (such as 300 seconds or 5 minutes) well in advance of making the changes. This ensures that any cached records will expire quickly, and the new records will be used sooner.
Verification of DNS Changes:
After reducing the TTL and making the change to the MX record, it is important to verify the propagation using tools like dig or nslookup.
Comparison with Other Options:
Change the email client configuration to match the MX record: Email clients generally do not need to match the MX record directly; they usually connect to a specific mail server specified in their settings.
Perform a DNS zone transfer prior to the MX record change: DNS zone transfers are used to replicate DNS records between DNS servers, but they are not related to the propagation of individual record changes.
Update the NS record to reflect the IP address change: NS records specify the DNS servers for a domain and are not related to MX record changes.
Reference: CompTIA Network+ study materials and DNS best practices.
Question #162
A customer wants to separate the finance department from the marketing department. The network administrator suggests segmenting the existing Class C network into two sections and readdressing all devices appropriately.
Which of the following subnet masks should the network administrator use?
- A . /24
- B . /25
- C . /26
- D . /27
Correct Answer: B
B
Explanation:
The correct answer is /25, which is the appropriate subnet mask for dividing an existing Class C network into two equal subnets. According to the CompTIA Network+ N10-009 objectives, subnetting is a core networking concept used to improve network segmentation, performance, and security.
A Class C network uses a default subnet mask of /24 (255.255.255.0), which provides 256 total addresses (254 usable). To split this network into two sections, the administrator must borrow one host bit from the last octet. Borrowing one bit results in a /25 subnet mask (255.255.255.128). This creates two subnets, each with 128 total addresses (126 usable)―an ideal solution for separating two departments such as finance and marketing.
A /24 would not create any segmentation, as it represents the original single network. A /26 would create four subnets, and a /27 would create eight subnets, both of which exceed the requirement of only two sections and unnecessarily reduce the number of available host addresses per subnet.
The Network+ objectives emphasize selecting subnet masks based on organizational requirements, balancing the number of subnets with sufficient host capacity. In this scenario, /25 is the most efficient and correct choice.
B
Explanation:
The correct answer is /25, which is the appropriate subnet mask for dividing an existing Class C network into two equal subnets. According to the CompTIA Network+ N10-009 objectives, subnetting is a core networking concept used to improve network segmentation, performance, and security.
A Class C network uses a default subnet mask of /24 (255.255.255.0), which provides 256 total addresses (254 usable). To split this network into two sections, the administrator must borrow one host bit from the last octet. Borrowing one bit results in a /25 subnet mask (255.255.255.128). This creates two subnets, each with 128 total addresses (126 usable)―an ideal solution for separating two departments such as finance and marketing.
A /24 would not create any segmentation, as it represents the original single network. A /26 would create four subnets, and a /27 would create eight subnets, both of which exceed the requirement of only two sections and unnecessarily reduce the number of available host addresses per subnet.
The Network+ objectives emphasize selecting subnet masks based on organizational requirements, balancing the number of subnets with sufficient host capacity. In this scenario, /25 is the most efficient and correct choice.
Question #163
Which of the following should a company implement in order to share a single IP address among all the employees in the office?
- A . STP
- B . BGP
- C . PAT
- D . VXLAN
Correct Answer: C
C
Explanation:
PAT (Port Address Translation) allows multiple devices on a local network to share a single public IP address when accessing the internet. It translates the private IP addresses to a single public IP with different port numbers for each session.
The document states:
“PAT (Port Address Translation) allows multiple devices on a LAN to share a single public IP address by assigning unique port numbers to each session, enabling internet connectivity for all devices.”
C
Explanation:
PAT (Port Address Translation) allows multiple devices on a local network to share a single public IP address when accessing the internet. It translates the private IP addresses to a single public IP with different port numbers for each session.
The document states:
“PAT (Port Address Translation) allows multiple devices on a LAN to share a single public IP address by assigning unique port numbers to each session, enabling internet connectivity for all devices.”
Question #164
Which of the following OSI model layers can utilize a connectionless protocol for data transmission?
- A . Physical
- B . Network
- C . Transport
- D . Application
Correct Answer: B
B
Explanation:
The Network layer (Layer 3 of the OSI model) can utilize the connectionless protocol IP (Internet Protocol) to send data packets independently without establishing a connection. This approach is typical for protocols like IP, which provide best-effort delivery rather than guaranteed delivery.
The document explains:
“The OSI Network Layer is responsible for logical addressing and routing, and it can utilize connectionless protocols like IP to send packets without requiring a session setup. This layer does not guarantee packet delivery, relying on higher layers for error detection or correction if needed.”
B
Explanation:
The Network layer (Layer 3 of the OSI model) can utilize the connectionless protocol IP (Internet Protocol) to send data packets independently without establishing a connection. This approach is typical for protocols like IP, which provide best-effort delivery rather than guaranteed delivery.
The document explains:
“The OSI Network Layer is responsible for logical addressing and routing, and it can utilize connectionless protocols like IP to send packets without requiring a session setup. This layer does not guarantee packet delivery, relying on higher layers for error detection or correction if needed.”
Question #165
A virtual machine has the following configuration:
• IPv4 address: 169.254.10.10
• Subnet mask: 255.255.0.0
The virtual machine can reach collocated systems but cannot reach external addresses on the Internet.
Which of the following Is most likely the root cause?
- A . The subnet mask is incorrect.
- B . The DHCP server is offline.
- C . The IP address is an RFC1918 private address.
- D . The DNS server is unreachable.
Correct Answer: B
B
Explanation:
Understanding the 169.254.x.x Address:
An IPv4 address in the range of 169.254.x.x is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unavailable.
DHCP Server Offline:
APIPA Assignment: When a device cannot obtain an IP address from a DHCP server, it assigns itself an APIPA address to enable local network communication. This allows communication with other devices on the same local subnet but not with external networks.
Resolution: Ensure the DHCP server is operational. Check for connectivity issues between the virtual machine and the DHCP server, and verify the DHCP server settings.
Comparison with Other Options:
The subnet mask is incorrect: The subnet mask 255.255.0.0 is appropriate for the 169.254.x.x range and does not prevent external access by itself.
The IP address is an RFC1918 private address: RFC1918 addresses are private IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) but 169.254.x.x is not one of them.
The DNS server is unreachable: While this could affect name resolution, it would not prevent the assignment of a non-APIPA address or local network communication.
Troubleshooting Steps:
Verify the DHCP server’s status and connectivity.
Restart the DHCP service if necessary.
Renew the IP lease on the virtual machine using commands such as ipconfig /renew (Windows) or dhclient (Linux).
Reference: CompTIA Network+ study materials on IP addressing and DHCP troubleshooting.
B
Explanation:
Understanding the 169.254.x.x Address:
An IPv4 address in the range of 169.254.x.x is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unavailable.
DHCP Server Offline:
APIPA Assignment: When a device cannot obtain an IP address from a DHCP server, it assigns itself an APIPA address to enable local network communication. This allows communication with other devices on the same local subnet but not with external networks.
Resolution: Ensure the DHCP server is operational. Check for connectivity issues between the virtual machine and the DHCP server, and verify the DHCP server settings.
Comparison with Other Options:
The subnet mask is incorrect: The subnet mask 255.255.0.0 is appropriate for the 169.254.x.x range and does not prevent external access by itself.
The IP address is an RFC1918 private address: RFC1918 addresses are private IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) but 169.254.x.x is not one of them.
The DNS server is unreachable: While this could affect name resolution, it would not prevent the assignment of a non-APIPA address or local network communication.
Troubleshooting Steps:
Verify the DHCP server’s status and connectivity.
Restart the DHCP service if necessary.
Renew the IP lease on the virtual machine using commands such as ipconfig /renew (Windows) or dhclient (Linux).
Reference: CompTIA Network+ study materials on IP addressing and DHCP troubleshooting.
Question #165
A virtual machine has the following configuration:
• IPv4 address: 169.254.10.10
• Subnet mask: 255.255.0.0
The virtual machine can reach collocated systems but cannot reach external addresses on the Internet.
Which of the following Is most likely the root cause?
- A . The subnet mask is incorrect.
- B . The DHCP server is offline.
- C . The IP address is an RFC1918 private address.
- D . The DNS server is unreachable.
Correct Answer: B
B
Explanation:
Understanding the 169.254.x.x Address:
An IPv4 address in the range of 169.254.x.x is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unavailable.
DHCP Server Offline:
APIPA Assignment: When a device cannot obtain an IP address from a DHCP server, it assigns itself an APIPA address to enable local network communication. This allows communication with other devices on the same local subnet but not with external networks.
Resolution: Ensure the DHCP server is operational. Check for connectivity issues between the virtual machine and the DHCP server, and verify the DHCP server settings.
Comparison with Other Options:
The subnet mask is incorrect: The subnet mask 255.255.0.0 is appropriate for the 169.254.x.x range and does not prevent external access by itself.
The IP address is an RFC1918 private address: RFC1918 addresses are private IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) but 169.254.x.x is not one of them.
The DNS server is unreachable: While this could affect name resolution, it would not prevent the assignment of a non-APIPA address or local network communication.
Troubleshooting Steps:
Verify the DHCP server’s status and connectivity.
Restart the DHCP service if necessary.
Renew the IP lease on the virtual machine using commands such as ipconfig /renew (Windows) or dhclient (Linux).
Reference: CompTIA Network+ study materials on IP addressing and DHCP troubleshooting.
B
Explanation:
Understanding the 169.254.x.x Address:
An IPv4 address in the range of 169.254.x.x is an Automatic Private IP Addressing (APIPA) address, assigned when a DHCP server is unavailable.
DHCP Server Offline:
APIPA Assignment: When a device cannot obtain an IP address from a DHCP server, it assigns itself an APIPA address to enable local network communication. This allows communication with other devices on the same local subnet but not with external networks.
Resolution: Ensure the DHCP server is operational. Check for connectivity issues between the virtual machine and the DHCP server, and verify the DHCP server settings.
Comparison with Other Options:
The subnet mask is incorrect: The subnet mask 255.255.0.0 is appropriate for the 169.254.x.x range and does not prevent external access by itself.
The IP address is an RFC1918 private address: RFC1918 addresses are private IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) but 169.254.x.x is not one of them.
The DNS server is unreachable: While this could affect name resolution, it would not prevent the assignment of a non-APIPA address or local network communication.
Troubleshooting Steps:
Verify the DHCP server’s status and connectivity.
Restart the DHCP service if necessary.
Renew the IP lease on the virtual machine using commands such as ipconfig /renew (Windows) or dhclient (Linux).
Reference: CompTIA Network+ study materials on IP addressing and DHCP troubleshooting.
Question #167
Which of the following allows the fastest recovery during a catastrophe event?
- A . Warm site
- B . Asynchronous replication
- C . Cold site
- D . Hot site
Correct Answer: D
D
Explanation:
The correct answer is D. Hot site. In CompTIA Network+ N10-009, disaster recovery and business continuity concepts include understanding recovery site types and how quickly they can restore operations after a major outage or catastrophe. A hot site provides the fastest recovery because it is a fully operational alternate location with the necessary network infrastructure, hardware, systems, connectivity, and often replicated data already available. Since the environment is prepared and ready to assume production workloads, organizations can fail over to a hot site with minimal downtime.
A warm site is partially prepared and may have network connectivity and some hardware in place, but it usually requires additional configuration, data restoration, or system activation before services can fully resume. A cold site provides only basic facilities, such as space, power, and cooling, but lacks most operational equipment and therefore has the longest recovery time. Asynchronous replication is a data replication method where changes are copied after they occur, but it is not itself a complete recovery location and may involve some data loss depending on timing.
Because the question asks which option allows the fastest recovery during a catastrophe, the best choice is a hot site.
D
Explanation:
The correct answer is D. Hot site. In CompTIA Network+ N10-009, disaster recovery and business continuity concepts include understanding recovery site types and how quickly they can restore operations after a major outage or catastrophe. A hot site provides the fastest recovery because it is a fully operational alternate location with the necessary network infrastructure, hardware, systems, connectivity, and often replicated data already available. Since the environment is prepared and ready to assume production workloads, organizations can fail over to a hot site with minimal downtime.
A warm site is partially prepared and may have network connectivity and some hardware in place, but it usually requires additional configuration, data restoration, or system activation before services can fully resume. A cold site provides only basic facilities, such as space, power, and cooling, but lacks most operational equipment and therefore has the longest recovery time. Asynchronous replication is a data replication method where changes are copied after they occur, but it is not itself a complete recovery location and may involve some data loss depending on timing.
Because the question asks which option allows the fastest recovery during a catastrophe, the best choice is a hot site.
Question #168
A network administrator deploys new network hardware. While configuring the network monitoring server, the server could authenticate but could not determine the specific status of the hardware.
Which of the following would the administrator most likely do to resolve the issue?
- A . Use the public community string
- B . Import the appropriate MIB
- C . Set up a switchport analyzer and forward traffic
- D . Configure SNMPv3 privacy
Correct Answer: B
B
Explanation:
MIBs (Management Information Bases) define the variables and objects that SNMP can query on a device. If the monitoring server authenticates but cannot interpret the data, it likely lacks the correct MIB for that vendor or model. Importing the proper MIB allows the monitoring server to correctly display device status and metrics.
B
Explanation:
MIBs (Management Information Bases) define the variables and objects that SNMP can query on a device. If the monitoring server authenticates but cannot interpret the data, it likely lacks the correct MIB for that vendor or model. Importing the proper MIB allows the monitoring server to correctly display device status and metrics.
Question #169
A technician needs to quickly set up a network with five wireless devices.
Which of the following network types should the technician configure to accomplish this task?
- A . Ad hoc
- B . Spine and leaf
- C . Point to point
- D . Mesh
Correct Answer: A
A
Explanation:
The correct answer is Ad hoc because it allows wireless devices to communicate directly with one another without requiring a centralized access point or additional infrastructure. According to CompTIA Network+ (N10-009) objectives under wireless networking concepts, an ad hoc network (also known as an Independent Basic Service Set, or IBSS) enables peer-to-peer wireless communication.
This type of network is ideal for temporary or quick setups where only a small number of devices need to connect. In an ad hoc configuration, each device connects directly to others, making it simple and fast to deploy without requiring switches, routers, or wireless access points.
Spine and leaf (Option B) is a data center architecture designed for high scalability and redundancy, not small wireless setups. Point-to-point (Option C) refers to a direct connection between two devices only, which would not support five devices efficiently. Mesh (Option D) allows multiple nodes to interconnect and provide redundancy, but it is more complex and typically requires compatible infrastructure devices.
Therefore, for a quick setup with five wireless devices, an ad hoc network is the most appropriate choice.
A
Explanation:
The correct answer is Ad hoc because it allows wireless devices to communicate directly with one another without requiring a centralized access point or additional infrastructure. According to CompTIA Network+ (N10-009) objectives under wireless networking concepts, an ad hoc network (also known as an Independent Basic Service Set, or IBSS) enables peer-to-peer wireless communication.
This type of network is ideal for temporary or quick setups where only a small number of devices need to connect. In an ad hoc configuration, each device connects directly to others, making it simple and fast to deploy without requiring switches, routers, or wireless access points.
Spine and leaf (Option B) is a data center architecture designed for high scalability and redundancy, not small wireless setups. Point-to-point (Option C) refers to a direct connection between two devices only, which would not support five devices efficiently. Mesh (Option D) allows multiple nodes to interconnect and provide redundancy, but it is more complex and typically requires compatible infrastructure devices.
Therefore, for a quick setup with five wireless devices, an ad hoc network is the most appropriate choice.
Question #170
A network administrator manages multiple computers and notices that three computers are no longer communicating with the network.
Which of the following commands best identifies whether other devices are restricting packet traffic?
- A . ipconfig
- B . traceroute
- C . nmap
- D . ping
Correct Answer: B
B
Explanation:
The correct answer is B. traceroute. Traceroute is a diagnostic command used to track the path that packets take from a source device to a destination across an IP network. It identifies each hop (router or intermediary device) along the route and measures the time it takes for packets to travel between them. This makes it particularly useful for determining where communication is failing or being restricted.
In this scenario, the administrator suspects that other network devices may be restricting traffic, such as routers, firewalls, or access control devices. Traceroute helps pinpoint exactly where packets stop or experience delays, indicating a potential filtering or blocking point in the network path.
The other options are less appropriate. ipconfig is used to view or manage a device’s local IP configuration and does not test packet flow across the network. Nmap is a scanning tool used to identify open ports and services, not to trace packet paths. Ping verifies basic connectivity but does not provide insight into intermediate devices or where traffic may be blocked.
According to CompTIA Network+ objectives, traceroute is the best tool for identifying routing issues and determining whether network devices are restricting traffic.
B
Explanation:
The correct answer is B. traceroute. Traceroute is a diagnostic command used to track the path that packets take from a source device to a destination across an IP network. It identifies each hop (router or intermediary device) along the route and measures the time it takes for packets to travel between them. This makes it particularly useful for determining where communication is failing or being restricted.
In this scenario, the administrator suspects that other network devices may be restricting traffic, such as routers, firewalls, or access control devices. Traceroute helps pinpoint exactly where packets stop or experience delays, indicating a potential filtering or blocking point in the network path.
The other options are less appropriate. ipconfig is used to view or manage a device’s local IP configuration and does not test packet flow across the network. Nmap is a scanning tool used to identify open ports and services, not to trace packet paths. Ping verifies basic connectivity but does not provide insight into intermediate devices or where traffic may be blocked.
According to CompTIA Network+ objectives, traceroute is the best tool for identifying routing issues and determining whether network devices are restricting traffic.