Virtual Machine is unable to ping its default gateway

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

• The IP address is configured correctly in the virtual machine (Guest Operating System).
• The virtual machine is unable to ping its own default gateway. 
• However, the virtual machine's IP address is reachable from the physical switch/router.

Environment

VMware vSphere ESXi

VMware vCenter

Cause

The virtual machine's IP is resolving to a different MAC address on the physical switch, indicating an IP conflict because another system on the network is using the same IP.

Resolution

Fix the IP conflict by configuring a unique IP address on the virtual machine and ensuring no other devices/virtual machines in the environment are using the same IP.

If the IP is resolving to a different Virtual Machine hosted in vCenter, you can find that VM using it's MAC address in the vCenter global search section.

Additional Information

The example commands below for viewing the ARP/MAC table may vary depending on the physical switch type; please engage the physical switch vendor to check the ARP/MAC table on the physical switch.

#show ip arp: Displays the entire ARP table.
#show ip arp [ip-address]: Shows ARP information for a specific IP address.
#show ip arp [interface]: Displays ARP entries learned on a specific interface (e.g., FastEthernet0/1).
#show ip arp vrf [vrf-name]: Displays ARP entries for a specific Virtual Routing/VLAN tunnel.

Note: This is one potential reason why the virtual machine's gateway is unreachable; however, if this is not your situation, please review the following KB article for further troubleshooting:

Troubleshooting virtual machine default gateway connection issues