Listed below is a quick list of tools that can be used to troubleshoot connectivity issue.
Ping
Ping can be used to verify connectivity between end devices. Note – A device such as a firewall may block the ICMP packet.
Tracert
Shows routing paths from source to destination on a PC.
Telnet
Telnet can be used to connect to a router/switch although data is sent in plain text
SSH
Same as Telnet, but data is encrypted.
Ipconfig /all
Display IP information that can be verified against network documentation. IP/Subnet mask/Default gateway information can be seen. DNS/WINS is also provided.
arp -a
Shows the MAC address table from a PC.
show ip arp
Shows the MAC address table from a router/switch.