professor Messer - troubleshooting networks

Question 1

• Do you have a link light?
  
  • Is it plugged in?
• Ping loopback (127.0.0.1)
  
  • Is the protocol stack working?
  • Availability and intermittent connectivity
• Ping local IP address
  
  • Checks local configuration, adapter, and link signal
• Ping default gateway
  
  • Connectivity on the local network
• Ping devices on router’s other side
  
  • 8.8.8.8

Answer 1

no network connectivity

Question 2

APIPA

Answer 2

Automatic Private IP Addressing

Question 3

• A link-local address
• No forwarding by routers
• IETF has allocated 169.254.1.0 through
169.254.254.255
• 169.254.0.0/24 and 169.254.255.0/24 are
reserved
• Automatically assigned
• Uses ARP to confirm the address isn’t currently in use
• Check your IP address
• Is it an APIPA address?

Answer 3

Automatic Private IP Addressing

Question 4

• Shares
• Server unavailable
• Share permissions have been modified
• Relies on DNS to find the server
• Printers
• Device sharing printer (or printer) is unavailable
• Printer permissions have been modified
• Email
• Service is associated with a specific server
• May be a cluster of servers
• Problems may be related to the servers or the
network path

Answer 4

Local resources unavailable

Question 5

• Windows alert in the system tray
  
  • “Limited or No connectivity”
  • “No Internet Access”
• Check the local IP address
  
  • An APIPA address will only have local connectivity
• If DHCP address is obtained, perform the ping tests
  
  • Local gateway, remote IP address

Answer 5

Limited or no connectivity

Question 6

• Internet access
  
  • Then nothing
• Check the system tray
  
  • A broken LAN icon is a loss of signal
  • Check for a cable problem
  • Might have bad network interface
• Problem with switch or wireless access point
  
  • Bad interfaces
  • Router rebooting

Answer 6

Intermittent connectivity

Question 7

• DHCP helps
  
  • But static addresses can conflict
• Windows will identify a duplicate
  
  • And prevent a conflict
• Two identical IP addresses will conflict
  
  • Intermittent connectivity, if any
• Reboot or reset the NIC
  
  • Start over from the beginning

Answer 7

IP conflicts

Question 8

• Frustrating to the user
  
  • Challenging to the technician
• Router or infrastructure congestion
  
  • Overloaded network or devices
• Speed and duplex incompatibility
  
  • An easy fix
• Hardware issue with the adapter
  
  • Or your cabling
• Malware infection

Answer 8

slow transfer speeds

Question 9

• Interference - Something else is using our frequency
• Signal strength
• Transmitting signal, transmitting antenna,
receiving antenna, etc.
• Incorrect channel
• Usually automatic; look for manual tuning
• Bounce and latency
• Multipath interference; flat surfaces
• Incorrect access point placement
• Locate close to the users

Answer 9

Low RF wireless signal

Question 10

• Predictable
  
  • Florescent lights
  • Microwave ovens
  • Cordless telephones
  • High-power sources
• Unpredictable
  
  • Multi-tenant building
• Measurements
  
  • Signal strength
  • Performance Monitor

Answer 10

wireless interference

Question 11

• Network name doesn’t appear
  
  • Other networks are there
• Too far away
  
  • Local networks are louder
• Wireless router has disabled SSID advertisements
  
  • It will never appear on a list
  • You can still manually connect

Answer 11

SSID not found