5.5 - CompTIA A+ Core 1

Common symptoms

No wireless connectivity

• To resolve:

  1. Ensure you have a link light (i.e., the device is plugged in)

  2. Ping the loopback address (127.0.0.1) to check if the protocol stack/network adapter works

  3. Ping your local IP address

  4. Ping another device on the local network (e.g., the default gateway)

  5. Ping an external IP address (e.g., 8.8.8.8).

Intermittent wireless connectivity

• To resolve:

  1. Try switching to a frequency with less interference

  2. Try increasing signal strength by moving closer to an access point, switching wireless antennas, or connecting an external wireless antenna

  3. Try switching to the correct channel/a channel with less interference

  4. Try moving the access point to a central location with limited multipath interference/obstacles

Slow network speeds

• To resolve:

  1. Validate network connectivity via a ping or a speed test - if speeds are high, the network isn’t the issue

  2. Evaluate connectivity on each network hop/segment

  3. Use multiple packet captures to evaluate network speeds

Limited connectivity

• To resolve:

  1. Check local/device IP addresses (e.g., for APIPA addresses).

  2. Ping the local gateway

  3. Ping a remote IP address

Jitter

• Jitter: Refers to the time between frames/packets over a network. Excessive jitter can cause a loss of information (choppy voice calls).

  • High jitter values cause inconsistent times between information; some may be transmitted at a rapid speed, and there may be a delay between other packets.

Poor Voice over Internet Protocol (VoIP) quality

• To resolve:

  1. Check Internet connectivity/speed tests

  2. Check/upgrade networking equipment (e.g., routers)

  3. Use a packet capture to check network performance

Port flapping

• Port flapping: Occurs when a network interface has intermittent availability (link light flashes on and off).

• To resolve:

  1. Verify the cable used in the patch panel is in good condition.

  2. Move cables between switch interfaces

  3. Replace bad hardware or cables

High latency

• Latency: Delay between network requests and responses.

• To resolve:

  1. Examine response times at every step/hop along a network path

  2. Use packet captures to examine latency

External interference

• Use a network performance monitor to track the signal-to-noise ratio (SNR) - a low ratio indicates high external interference.

Authentication failures

• Accessing resources requires proper credentials, like a username, password, or other factors

• To resolve:

  1. Attempt to log out and log back in

  2. Use a packet capture to verify that authentication failures are the issue

Intermittent internet connectivity

• To resolve:

  1. Use recurring pings/captures to detect poor network connectivity

  2. Work with a third-party provider (e.g., an ISP) for support

  3. Check your service level agreement (SLA) to determine regular downtime/connectivity stats