When is a network baseline performed, what does it tell you, and what information does it show?
It is performed right after network install.
It tells you the optimal performance of the network
The information is shows:
1. Network activity
2. Connected devices
3. Network resources
Regardless of the issues users are experiencing, what tasks should you perform first when troubleshooting a networking issue?
- Verify that the network cable is plugged into the computer, wall jack, and network switch.
- Use a cable tester to verify the network cable is functioning properly.
- Check the link activity light on the network adapter and the network switch.
- Confirm that all network equipment such as servers, routers, and switches are powered on and operating properly.
What troubleshooting steps do you perform when users are experiencing slow network speeds?
- Verify that the network infrastructure supports the network speed. For example, if the network is designed to operate at speeds up to 1 Gbps, but the switch can handle only 100 Mbps, the entire network will run at 100 Mbps.
- Check for malware or other unwanted software running on the network. Many malware programs are designed to use up as much network bandwidth as possible. This will result in very slow network speeds.
- Make sure the network adapter drivers are up to date.
- In the properties of the network adapter, make sure full-duplex mode, not half-duplex, is set.
A. In full-duplex mode, the network adapter can send and receive data simultaneously.
B. In half-duplex mode, the network adapter can only transmit or receive data at a time, not both simultaneously.
What is latency and what is a common cause for high latency?
Latency is the amount of time it takes to send a network request and receive a response back.
Port Flapping is a common cause for high latency?
What is Port Flapping?
This is when a port on the network switch continuously turns off and on three or more times per second for at least 10 seconds.
What steps do you take if port flapping is occurring?
- Reseat the network cable.
- Move the network cable to another port on the switch.
- Replace the network cable.
- Escalate the problem to the network engineer if the issue persists.
What does it mean when there is limited network connectivity?
It means that a particular network resource cannot be accessed.
After verifying all hardware is working properly, perform the following steps to troubleshoot network connectivity issues.
- Ping the localhost (also known as the loopback) address 127.0.0.1. This is an IP address that is reserved on all network adapters. If the ping request is successfully sent and received, the TCP/IP protocol is installed and working properly.
- Ping the device’s IP address. If this ping request is successful, the IP configuration is correct and the network adapter is operating properly.
- Ping the local network’s gateway. If successful, the device can communicate across the local network.
- Ping an external resource, such as a web server. If successful, the device can communicate outside of the network.
What is APIPA?
Automatic IP Addressing
It means the DHCP server could not be reached and you get an IPv4 address that begins with 169.254.
What can you do temporarily if the DHCP server is down
Set the IP configuration manually with a static IP address
What DNS issues can lead to limited network connectivity?
- A remote device that can be pinged using the IP address, but not the hostname signifies an issue with DNS.
- You should verify the DNS server information is set correctly on the local device. If it is, the issue is likely the DNS server. You must escalate the issue.
What can you do to alleviate wireless network interference?
- Changing the channel of the wireless network usually fixes the problem.
- Relocating the external device or wireless access point may help alleviate interference.
What can you do to alleviate weak signal strength in a wireless network?
- Performing a site survey can help determine if there are weak spots in the wireless network.
- Moving the wireless access point or adding a network extender can increase the signal strength.
What is VoIP and how does it work?
Voice over IP.
It sends voice data over the IP network.
What things can affect the quality of a VoIP network?
Quality of Service (QOS)
High latency
Jitter
How does Quality of Service affect VoIP calls?
- Network switches and routers can determine the type of traffic based on the information contained in the packet headers.
- You can configure QoS settings to give priority to VoIP traffic over other network traffic. This helps ensure that there will be enough bandwidth available for VoIP traffic.
How can latency affect VoIP calls?
- High latency causes VoIP callers to talk over each other because the delay between the user speaking and the other user hearing what is said can be a few seconds.
- Experts advise that 150 milliseconds one way is the maximum level of latency that is acceptable in VoIP systems.
- The lower the latency, the better the VoIP quality will be.
- When a VoIP server is hosted in the cloud, network latency may increase due to internet latency.
What is Jitter?
Jitter is the variation in the latency of VoIP packets. The goal is to have a steady stream of data packets during a VoIP call.
When troubleshooting Jitter, what should you check first?
Quality of Service (QOS)
What are the common causes of Jitter?
Network Congestion
Using a wireless network for VoIP communication
Bad hardware
If you are unable to correct the source of the Jitter, what can be used to help?
Jitter buffers on the endpoints
Why is best to only use Jitter buffers as a last resort?
They can introduce latency issues
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Networking - Command Line Network Utilities57
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Networking - Network Troubleshooting22
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Mobile Devices - Laptop Facts20
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Mobile Devices - Mobile Device Displays & Components9
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Mobile Devices - Laptop Power Facts17
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Mobile Devices - Mobile Devices33
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Mobile Devices - Wireless and Cellular Data Connections29
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Mobile Devices - MDM & Synchronization4
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Mobile Decives - Mobile Email Configuration4
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Ports and Protocols20
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Security - Workstation Security24
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Security - Security Policies4
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Security - Incident Response9
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Security - Regulated Data17
