Troubleshoot Network Issues Flashcards
What are the three categories to isolate network issues?
- Local issues
- Network issues
- Service issues
What two main tools does macOS offer for diagnosing network issues
Network Preferences and Terminal
What are the three network status indicators and what do they mean?
- Green- Connection is active and configured with TCP/IP settings
- Yellow- Connection is active but the TCP/IP settings aren’t properly configured
- Red- Indicates either improperly configured network settings or disconnected network interfaces.
What are the four most common network issues to check for before doing a deep dive into larger issues?
- Ethernet connectivity
- Wi-Fi connectivity
- DHCP services
- DNS services
What steps should you take to troubleshoot an Ethernet connectivity issue?
- Verify physical connection
- Verify ethernet cable with known-good cable
- If possible, verify ethernet port, with a known-good port
- Verify ethernet adapter with known-good adapter
- Manually set a slower speed in the advanced hardware settings of Network preferences.
How does a Mac indicate that there is a problem with the wireless network?
The Wi-Fi status menu shows an exclamation point (!)
How do you access the Wireless Diagnostic tool?
Press and hold the option key and click on the Wi-Fi status icon in the menu bar.
Where is the compressed archive that the Wireless Diagnostic tool stored on the Mac?
/private/var/tmp
What happens when you configure a Mac to use DHCP and the DHCP server runs out of available networks?
The Mac might be able to communicate with other devices on the LAN even though it doesn’t have access to WAN or internet resources.
What should you do first if you are having DNS service issues?
Verify the DNS server configuration in Network preferences. In most cases the top-listed network service interface is primary, and macOS uses it for DNS resolution with the exception of if the primary network service lacks a router configuration, in which case the DNS resolution falls to the next fully configured network service interface.
What are some of the main network identification and diagnostic commands that you can access in Terminal?
- ifconfig- inspect details regarding hardware network interfaces)
- netstat (network status)- View routing information and network stats
- ping- test network connectivity and latency)
- nslookup, dig, host, and dscacheutil- Test DNS resolution
- traceroute- Analyze how your network connection are routed to their destination
- nc (netcat)- Test the quality of a network connection
How can you identify the MAC addresses for all the Mac computer’s network interfaces?
From the “ether” line in the output of the “ifconfig” command in terminal.
What’s the term for the current data rate of a Wi-Fi connection
Tx Rate
How can you verify basic connectivity to another network host, and how does it work?
The “ping” terminal command. You send a ping packet in terminal and wait for its return.
How can you verify that the DNS host name resolution is working?
Terminal commands: nslookup, dig, host, or dscacheutil
