Section 23: Troubleshooting Network Issues

Question 1

What is a Startup Configuration?

Answer 1

Stored in the NVRAM and contains the commands needed to initially configure a router

Question 2

What is a Running Configuration?

Answer 2

It’s actively being used by the router at that moment

Question 3

What is a VLAN Assignment?

Answer 3

A practice of segmenting an IT organization’s network, separating users into respective network sections

Question 4

What is a Network Performance Baseline?

Answer 4

Defines the normal working conditions of an enterprise network infrastructure.

Question 5

What is a Collision?

Answer 5

Occurs when two hosts on the network transmit at the same time which causes the signals to combine on the network medium.

Question 6

What is a Broadcast Storm?

Answer 6

Occurs when a network system is overwhelmed by continuous multicast or broadcast traffic

Question 7

What is a Duplicate IP Address?

Answer 7

Occurs when another computer on the same network has an identical IP to another workstation or server on the same network.

Question 8

What is Multicast Flooding?

Answer 8

No specific host is associated with the multicast MAC address in the CAM table of the switch.

Question 9

What is Asymmetrical Routing?

Answer 9

Network packets leave via one path and return via a different path.

Question 10

What are Switching Loops?

Answer 10

An issue with how STP is configured

Spanning Tree Protocol (STP)

Question 11

What are Routing Loops?

Answer 11

Formed when an error occurs in the operation of the routing algortihm and creates a circular route amongst a group of network devices.

Caused by logical L3 circular connections that may exist in routing

Question 12

What is a Rogue DHCP Server?

Answer 12

A DHCP server on a network which is not under the administrative control of the network administrators.

Question 13

What is a DHCP Scope Exhaustion?

Answer 13

Pccurs when the DHCP server runs out of valid IPs to assign to the clients requesting access on the network.

Question 14

What is a Missing Route?

Answer 14

When a router cannot reach a destination because there is a missing route in the routing table.

Question 15

What is a Low Optical Link Budget?

Answer 15

A calculation that considers all the anticipated losses along the length of a fiber optic connection

Happens due to the distance of the cable or damage caused to the cable

Question 16

What could be the cause of some Certificate Issues? List at least 2 of the 3

Answer 16

• Digital certificate is not signed by a trusted certificate authority
• It has already expired
• The server didn’t have a certificate associated with a trusted route certificate

Question 17

What is a Host-Based Firewall?

Answer 17

Runs on an individual computer or device connected to the network to protect that one device.

Question 18

What is a Network-Based Firewall?

Answer 18

Deployed in line with the network traffic flow to monitor and filter incoming and outgoing network traffic based on established rule sets.

Question 19

What could be 3 issues for Host-Based & Network-Based Firewalls?

Answer 19

• Access to protected resources from unprotected networks is not working
• Access to unprotected resources from protected networks is not working
• Access to the firewall and its configurations is not working

Question 20

What is does a DNS do?

Answer 20

Matches domain names with the corresponding IP addresses used by a server.

Question 21

What could be 4 issues with DNS?

Answer 21

• Connectivity between client and DNS server
• A records and CNAME records not properly created
• High CPU usage (increases latency, jitter, and packet loss)
• Time to Live (TTL) is not set correctly

Question 22

What does NTP do?

Answer 22

Allows synchronization of system clocks between different layers of a hierarchical, semi-layered system of time sources.

Question 23

What could be 3 issues for NTP?

Answer 23

• Packets are not received
• Packets are not processed
• Errors or packet loss

Question 24

What could be a Licensed Feature Issue?

Answer 24

People who use the things and install the devices are not the same ones who are empowered to make purchasing decisions

Question 25

What are 2 challenges with a BYOD policy?

Answer 25

• Decrease in capital expenditures
• Increase in operational expenditures

Question 26

What are some Network Performance Issues? Name at least 3

Answer 26

• High CPU usage
• High bandwidth usage
• Poor connectivity
• Network malfunction
• DNS problems

Question 27

How would one fix a high CPU usage problem in the network?

Answer 27

To upgrade the network devices to more powerful ones such as enterprise class routers and firewalls.

Or simplify the processing load

Question 28

How would one fix a high bandwidth usage problem in the network?

Answer 28

Increase the bandwidth size by paying more to your ISP or do a network flow analysis and determine what sites and traffic types are being used by clients.

Question 29

How would one fix a poor connectivity problem in a network?

Answer 29

Check the cables and test them one by one

Use a cable tester for twisted pair/A fiber light meter for fiber optic

Question 30

What could be the cause for a network malfunction?

Answer 30

By using old or outdated network operating systems