# Computer Networks/Monitoring and Troubleshooting

This lesson covers network monitoring and troubleshooting for CompTIA Network+ Certification.

## Objectives and Skills

Objectives and skills for the network monitoring and troubleshooting portion of Network+ certification include:
* Given a scenario, use appropriate monitoring tools
** Packet/network analyzer
** Interface monitoring tools
** Port scanner
** Top talkers/listeners
** SNMP management software
*** Trap
*** Get
*** Walk
*** MIBS
** Alerts
*** Email
*** SMS
** Packet flow monitoring
** SYSLOG
** SIEM
** Environmental monitoring tools
*** Temperature
*** Humidity
** Power monitoring tools
** Wireless survey tools
** Wireless analyzers
* Given a scenario, analyze metrics and reports from monitoring and tracking performance tools
** Baseline
** Bottleneck
** Log management
** Graphing
** Utilization
*** Bandwidth
*** Storage
*** Network device CPU
*** Network device memory
*** Wireless channel utilization
** Link status
** Interface monitoring
*** Errors
*** Utilization
*** Discards
*** Packet drops
*** Interface resets
*** Speed and duplex
* Given a scenario, implement the following network troubleshooting methodology
** Identify the problem
*** Gather information
*** Duplicate the problem, if possible
*** Question users
*** Identify symptoms
*** Determine if anything has changed
*** Approach multiple problems individually
** Establish a theory of probable cause
*** Question the obvious
*** Consider multiple approaches
**** Top-to-bottom/bottom-to-top OSI model
**** Divide and conquer
** Test the theory to determine cause
*** Once theory is confirmed, determine next steps to resolve problem
*** If theory is not confirmed, re-establish new theory or escalate
** Establish a plan of action to resolve the problem and identify potential effects
** Implement the solution or escalate as necessary
** Verify full system functionality and if applicable implement preventative measures
** Document findings, actions, and outcomes
* Given a scenario, troubleshoot and resolve common network issues
** Incorrect IP configuration/default gateway
** Broadcast storms/switching loop
** Duplicate IP
** Speed and duplex mismatch
** End-to-end connectivity
** Incorrect VLAN assignment
** Hardware failure
** Misconfigured DHCP
** Misconfigured DNS
** Incorrect interface/interface misconfiguration
** Cable placement
** Interface errors
** Simultaneous wired/wireless connections
** Discovering neighboring devices/nodes
** Power failure/power anomalies
** MTU/MTU black hole
** Missing IP routes
** NIC teaming misconfiguration
*** Active-active vs active-passive
*** Multicast vs broadcast

## Readings

* Wikipedia: Network monitoring
* Wikipedia: Troubleshooting

## Multimedia

* YouTube: Using Protocol Analyzers - CompTIA Network+ N10-006 - 2.1
* YouTube: Network Monitoring Tools - CompTIA Network+ N10-006 - 2.1
* YouTube: SIEM - CompTIA Network+ N10-006 - 2.1
* YouTube: Environmental Monitoring Tools - CompTIA Network+ N10-006 - 2.1
* YouTube: Wireless Tools - CompTIA Network+ N10-006 - 2.1
* YouTube: Baselines and Bottlenecks - CompTIA Network+ N10-006 - 2.2
* YouTube: Log Management and Graphing - CompTIA Network+ N10-006 - 2.2
* YouTube: Utilization Statistics - CompTIA Network+ N10-006 - 2.2
* YouTube: Interface Monitoring - CompTIA Network+ N10-006 - 2.2
* YouTube: Network Troubleshooting Methodology - CompTIA Network+ N10-006 - 4.1
* YouTube: Troubleshooting IP Configurations - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting DNS and DHCP - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting Broadcast Storms and Switching Loops - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting Interface Configurations - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting VLAN Assignments - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting Network Connectivity - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting Mismatched MTUs - CompTIA Network+ N10-006 - 4.6
* YouTube: Troubleshooting NIC Teaming - CompTIA Network+ N10-006 - 4.6

## Activities

* Research free network monitoring software. Compare the different tools available and select one to download and install on your test network. Configure the software to monitor at least one networked device and one computer.
* Research free Wi-Fi site survey / coverage tools. Compare the different tools available and select one to download and install on your test network. Run the software and survey your wireless network for signal strength, interference, and rogue access points.
* Using a recent or current issue on your network, follow the CompTIA-recommended troubleshooting methodology to resolve the issue:
** Identify the problem
** Establish a theory of probable cause
** Test the theory to determine cause
** Establish a plan of action to resolve the problem and identify potential effects
** Implement the solution or escalate as necessary
** Verify full system functionality and if applicable implement preventative measures
** Document findings, actions, and outcomes
* Identify and test the appropriate approach and utilities to use when troubleshooting the following network issues:
** Incorrect IP configuration/default gateway
** Broadcast storms/switching loop
** Duplicate IP
** Speed and duplex mismatch
** End-to-end connectivity
** Incorrect VLAN assignment
** Hardware failure
** Misconfigured DHCP
** Misconfigured DNS
** Incorrect interface/interface misconfiguration
** Cable placement
** Interface errors
** Simultaneous wired/wireless connections
** Discovering neighboring devices/nodes
** Power failure/power anomalies
** MTU/MTU black hole
** Missing IP routes
** NIC teaming misconfiguration