5. Troubleshooting IP Addressing Flashcards
1
Q
What are the four steps in troubleshooting an IP connectivity issue?
A
- ping 127.0.0.1 (loopback)
- ping 172.16.10.2 (own IP address)
- ping 172.16.10.1 (default gateway)
- ping 172.16.20.2 (target IP address)
2
Q
What could a ping timeout indicate?
A
This can indicate that the ping reached the destination, but failed to return, ie a router can pass the packet correctly in one direction but not the other
Failure to reach the destination is usually notified by an ICMP message from the last device in the path, ie a router may not know where to forward a packet and so drops it and sends an ICMP message
3
Q
When diagnosing IP addressing issues, what things should you look out for?
A
- Calculate the subnet for the IP address
- Check that all IP addresses used for hosts and gateways are valid i.e. do not fall on a network or broadcaster address.
4
Q
List useful Windows commands for diagnostics
A
- ping
- tracert
- arp -a
- ipconfig /all
5
Q
List useful Cisco IOS commands for diagnostics
A
- ping
- traceroute
- show ip arp
6
Q
List useful MacOS/Linux commands for diagnostics
A
- ping
- traceroute??
- ifconfig
- ipconfig getifaddr en0 (en1 for Ethernet)
- curl ifconfig.me
- curl ipecho.net/plain ; echo
