CompTIA Network+ Question C-28

A administrator’s network has OSPF for the internal routing protocol and has two interfaces that continue to flap. The administrator reviews the following output:
Fast ethernet 0 is up, line protocol is up
Int ip address is 10.20.130.5/25
MTU 1500 bytes, BW10000 kbit, DLY 100 usec Reliability 255/255, Tx load 1/255, Rx load 1/255 Encapsulation ospf, loopback not set
Keep alive 10
Full duplex, 100Mb/s, 100Base Tx/Fx Received 1052993 broadcasts
1258 input errors
983881 packet output, 768588 bytes
1747 output errors, 0 collisions, 423 resets

Which of the following problems would cause the interface flap?

A. Wrong IP address
B. Loopback not set
C. Bad wire
D. Incorrect encapsulation
E. Duplex mismatch

Correct Answer: E

CompTIA Network+ Question C-13

A technician, Peter, needs to troubleshoot a recently installed NIC. He decides to ping the local loopback address. Which of the following is a valid IPv4 loopback address?

A. 10.0.0.1
B. 127.0.0.1
C. 172.16.1.1
D. 192.168.1.1

Correct Answer: B

Explanation:
The loopback address is a special IP address that is designated for the software loopback interface of a computer. The loopback interface has no hardware
associated with it, and it is not physically connected to a network. The loopback address causes any messages sent to it to be returned to the sending system. The loopback address allows client software to communicate with server software on the same computer. Users specify the loopback address which will point back to the computer’s TCP/IP network configuration.
In IPv4, the loopback address is 127.0.0.1.
In IPv6, the loopback address is 0:0:0:0:0:0:0:1, more commonly notated as follows. ::1

CompTIA Network+ Question C-3

In a service provider network, a company has an existing IP address scheme. Company A’s network currently uses the following scheme: Company B uses the following scheme: Subnet 1: 192.168.1.50/28
The network administrator cannot force the customer to update its IP scheme. Considering this, which of the following is the BEST way for the company to connect these networks?

A. DMZ
B. PAT
C. NAT
D. VLAN

Correct Answer: C

CompTIA Network+ Question C-2

The administrator’s network has OSPF for the internal routing protocol. One port going out to the Internet is congested. The data is going out to the Internet, but queues up before sending. Which of the following would resolve this issue?
Output:
Fast Ethernet 0 is up, line protocol is up Int ip address is 10.20.130.5/25
MTU 1500 bytes, BW10000 kbit, DLY 100 usec Reliability 255/255, Tx load 1/255, Rx load 1/255 Encapsulation ospf, loopback not set
Keep alive 10
Half duplex, 100Mb/s, 100 Base Tx/Fx Received 1052993 broadcasts
0 input errors
983881 packets output, 768588 bytes
0 output errors, 0 collisions, 0 resets

A. Set the loopback address
B. Change the IP address
C. Change the slash notation
D. Change duplex to full

Correct Answer: D

Explanation:
From the output we see that the half-duplex is configured. This would not use the full capacity of ports on the network. By changing to full duplex the throughput would be doubled.
Note: All communications are either half-duplex or full-duplex. During half-duplex communication, a device can either send communication or receive communication, but not both at the same time. In full-duplex communication, both devices can send and receive communication at the same time. This means that the effective throughput is doubled and communication is much more efficient.

CompTIA Network+ Question B-99

A network technician has detected duplicate IP addresses on the network. After testing the behavior of rogue DHCP servers, the technician believes that the issue is related to an unauthorized home router. Which of the following should the technician do NEXT in the troubleshooting methodology?

A. Document the findings and action taken.
B. Establish a plan to locate the rogue DHCP server.
C. Remove the rogue DHCP server from the network.
D. Identify the root cause of the problem.

Correct Answer: B

Explanation:
By testing the behavior of rogue DHCP servers and determining that the issue is related to an unauthorized home router, the technician has completed the third step in the 7-step troubleshooting process. The next step is to establish a plan of action to resolve the problem and identify potential effects. Establishing a plan to locate the rogue DHCP server meets the requirements of this step.
1. Identify the problem. Information gathering. Identify symptoms. Question users.
Determine if anything has changed.
2. Establish a theory of probable cause. Question the obvious.
3. Test the theory to determine cause:
When the theory is confirmed, determine the next steps to resolve the problem. If theory is not confirmed, re-establish a new theory or escalate.
4. Establish a plan of action to resolve the problem and identify potential effects.
5. Implement the solution or escalate as necessary.
6. Verify full system functionality and if applicable implement preventive measures.
7. Document findings, actions, and outcomes.

CompTIA Network+ Question B-70

After repairing a computer infected with malware, a technician determines that the web browser fails to go to the proper address for some sites. Which of the following should be checked?

A. Server host file
B. Subnet mask
C. Local hosts file
D. Duplex settings

Correct Answer: C

Explanation:
The local hosts file is a text file that contains hostname-to-IP address mappings. By default, host to IP address mappings that are configured in the Hosts file supersede the information in DNS. If there is an entry for a domain name in the Hosts file, then the server will not attempt to query DNS servers for that name. Instead, the IP address that is configured in the Hosts file will be used. If the IP address corresponding to a name changes and the Hosts file is not updated, you may be unable to connect to the host.

CompTIA Network+ Question B-50

Which of the following describes an IPv6 address of ::1?

A. Broadcast
B. Loopback
C. Classless
D. Multicast

Correct Answer: B

Explanation:
The loopback address is a special IP address that is designated for the software loopback interface of a computer. The loopback interface has no hardware associated with it, and it is not physically connected to a network. The loopback address causes any messages sent to it to be returned to the sending system. The loopback address allows client software to communicate with server software on the same computer. Users specify the loopback address which will point back to the computer’s TCP/IP network configuration.
In IPv4, the loopback address is 127.0.0.1.
In IPv6, the loopback address is 0:0:0:0:0:0:0:1, which can be shortened to ::1

CompTIA Network+ Question B-49

A technician, Peter, has been tasked with assigning two IP addresses to WAN interfaces on connected routers. In order to conserve address space, which of the following subnet masks should Peter use for this subnet?

A. /24
B. /32
C. /28
D. /29
E. /30

Correct Answer: E

Explanation:
An IPv4 address consists of 32 bits. The first x number of bits in the address is the network address and the remaining bits are used for the host addresses. The subnet mask defines how many bits form the network address and from that, we can calculate how many bits are used for the host addresses.
In this question, the /30 subnet mask dictates that the first 30 bits of the IP address are used for network addressing and the remaining 2 bits are used for host addressing. The formula to calculate the number of hosts in a subnet is 2n – 2. The “n” in the host’s formula represents the number of bits used for host addressing. If we apply the formula (22 – 2), a /30 subnet mask will provide 2 IP addresses.

CompTIA Network+ Question B-38

A host has been assigned the address 169.254.0.1. This is an example of which of the following address types?

A. APIPA
B. MAC
C. Static
D. Public

Correct Answer: A

Explanation:
APIPA stands for Automatic Private IP Addressing and is a feature of Windows operating systems. When a client computer is configured to use automatic addressing (DHCP), APIPA assigns a class B IP address from 169.254.0.0 to 169.254.255.255 to the client when a DHCP server is unavailable.
When a client computer configured to use DHCP boots up, it first looks for a DHCP server to provide the client with IP address and subnet mask. If the client is unable to contact a DHCP server, it uses APIPA to automatically configure itself with an IP address from a range that has been reserved especially for Microsoft. The client also configures itself with a default class B subnet mask of 255.255.0.0. The client will use the self-configured IP address until a DHCP server becomes
available.