Troubleshooting connectivity issues

Single user or small group connectivity issues can be resolved by confirming that the networking functions required for a user workstation to access local and remote network resources are functioning properly. The basic requirements or items to confirm include:

• Enabling the correct network interface(s) (workstation configuration)

• Confirming layer 1 (physical) connectivity

• Obtaining an IP address, subnet mask, and default gateway for each interface (DHCP)

• Obtaining the MAC address of the default gateway or other local network services (ARP)

• Obtaining the IP address of a network service (DNS)

• Connecting to a network service (TCP handshake or UDP response)

We'll briefly discuss each of these in order; while the first two steps will not involve using Wireshark, they are a necessary part in a troubleshooting approach. If the connectivity issue is affecting a group of users or a whole office, the first step is probably not applicable.

Enabling network interfaces

While...