- (Topic 3)
An application is not working. When the log files are reviewed, the application continuously tries to reach the following destination:
Which of the following is most likely associated with this IP address?
Correct Answer:
D
The IP address ::1/128 is the loopback address of the local host in IPv6, which is the equivalent of the 127.0.0.1 in IPv4. The loopback address is a virtual interface that loops all traffic back to itself, the local host. The loopback address is used for testing and troubleshooting purposes, such as checking the connectivity and configuration of the network stack. If an application tries to reach the loopback address, it means that it is not communicating with any external network or server, but only with itself.
The other options are not correct because they are not associated with the IP address ::1/128. They are:
✑ APIPA. APIPA stands for Automatic Private IP Addressing, which is a feature that allows a device to assign itself a private IPv4 address in the range of 169.254.0.0/16 when no DHCP server is available. APIPA does not apply to IPv6 addresses, and it is not related to the loopback address.
✑ Default gateway. The default gateway is the IP address of the router or device that connects a local network to other networks. The default gateway is usually the first or last usable IP address in a subnet, and it is not the same as the loopback address.
✑ Link local. Link local addresses are IPv6 addresses that are used for communication within a single network segment or link. Link local addresses have the prefix fe80::/10, and they are not routable or reachable from other networks. Link local addresses are not the same as the loopback address.
References1: Loopback Address - ::1/128 - ipUpTime.net2: Network+ (Plus) Certification | CompTIA IT Certifications3: Reserved IP addresses - Wikipedia
- (Topic 3)
On a network with redundant switches, a network administrator replaced one of the switches but was unable to get a connection with another switch. Which of the following should the administrator chock after successfully testing the cable that was wired for TIA/EIA-568A on both ends?
Correct Answer:
A
Auto-MDIX (or medium dependent interface crossover) is a feature that automatically detects the type of cable connection and configures the interface accordingly
(i.e. straight-through or crossover). This ensures that the connection between the two switches is successful. This is referenced in the CompTIA Network+ Study Manual, page 519.
- (Topic 3)
After installing a new wireless access point, an engineer tests the device and sees that it is not performing at the rated speeds. Which of the following should the engineer do to troubleshoot the issue? (Select two).
Correct Answer:
AB
One possible cause of poor wireless performance is a bottleneck in the network, which means that other devices or applications are consuming too much bandwidth or resources and limiting the speed of the wireless access point. To troubleshoot this issue, the engineer should ensure that there is no congestion or interference from other devices on the network, such as wired clients, servers, routers, switches, or other wireless access points. The engineer can use tools such as network analyzers, bandwidth monitors, or ping tests to check the network traffic and latency12.
Another possible cause of poor wireless performance is outdated firmware on the device, which may contain bugs or vulnerabilities that affect the functionality or security of the wireless access point. To troubleshoot this issue, the engineer should install the latest firmware for the device from the manufacturer’s website or support portal. The engineer should follow the instructions carefully and backup the configuration before updating the firmware. The engineer can also check the release notes or changelog of the firmware to see if there are any improvements or fixes related to the wireless performance3 .
The other options are not relevant to troubleshooting poor wireless performance. Creating a new VLAN for the access point may help with network segmentation or security, but it will not improve the speed of the wireless connection. Making sure the SSID is not longer than 16 characters may help with compatibility or readability, but it will not affect the wireless performance. Configuring the AP in autonomous mode may give more control or flexibility to the engineer, but it will not enhance the wireless speed. Installing a wireless LAN controller may help with managing multiple access points or deploying advanced features, but it will not increase the wireless performance.
- (Topic 1)
A network engineer configured new firewalls with the correct configuration to be deployed to each remote branch. Unneeded services were disabled, and all firewall rules were applied successfully. Which of the following should the network engineer perform NEXT to ensure all the firewalls are hardened successfully?
Correct Answer:
C
Updating the firewalls with current firmware and software is an important step to ensure all the firewalls are hardened successfully, as it can fix any known vulnerabilities or bugs and provide new features or enhancements. Enabling an implicit permit rule is not a good practice for firewall hardening, as it can allow unwanted traffic to pass through the firewall. Configuring the log settings on the firewalls to the central syslog server is a good practice for monitoring and auditing purposes, but it does not harden the firewalls themselves. Using the same complex passwords on all firewalls is not a good practice for password security, as it can increase the risk of compromise if one firewall is breached. References: CompTIA Network+ Certification Exam Objectives Version 2.0 (Exam Number: N10-006), Domain 3.0 Network Security, Objective 3.3 Given a scenario, implement network hardening techniques.
- (Topic 3)
Which of the following protocols uses Dijkstra’s algorithm to calculate the LOWEST cost between routers?
Correct Answer:
B
OSPF stands for Open Shortest Path First and is a link-state routing protocol that uses Dijkstra’s algorithm to calculate the lowest cost between routers. OSPF assigns a cost value to each link based on factors such as bandwidth, delay, or reliability, and builds a map of the network topology. OSPF then uses Dijkstra’s algorithm to find the shortest path from each router to every other router in the network1. RIP stands for Routing Information Protocol and is a distance-vector routing protocol that uses hop count as the metric to find the best path. BGP stands for Border Gateway Protocol and is a path-vector routing protocol that uses attributes such as AS path, local preference, or origin to select the best route. EIGRP stands for Enhanced Interior Gateway Routing Protocol and is a hybrid routing protocol that uses a composite metric based on bandwidth, delay, load, and reliability.
References: 1 Dijkstra’s algorithm - Wikipedia (https://en.wikipedia.org/wiki/Dijkstra's_algorithm)
