VMware Network Troubleshooting

Walkthroughs and checks for common VMware networking issues.

VM Network Connectivity — Troubleshooting Guide

vDS environment · Start at Tier 1. Only descend when the current tier fully clears.

IP address & NIC state LinuxWindows
ip addr showipconfig /all
Check: correct IP, correct NIC, not 169.254.x.x (APIPA = DHCP failure)
Subnet mask
Wrong prefix breaks same-subnet reachability. /24 vs /25 is a silent killer. Verify prefix length matches the VLAN design.
Default gateway LinuxWindows
ip route show defaultroute print
Must be in same subnet as VM IP. Missing or wrong gateway = no off-subnet traffic.
Ping the gateway
ping -c 4 <gw-ip>
If no reply, check ARP before blaming the network.
ARP resolution LinuxWindows
arping -I eth0 -c 3 <gw-ip>arp -a
ARP fails with correct IP config → VLAN mismatch → move to Tier 2.
DNS
nslookup <host>dig <host>
Verify DNS servers are configured and reachable.
Beyond the gateway
ping 8.8.8.8traceroute 8.8.8.8
Test routing (8.8.8.8) then DNS+routing (google.com). Use traceroute to find where it dies.
NIC link state Linux
ethtool eth0
Look for "Link detected: yes" and VMXNET3 driver. UP with no LOWER_UP = VMware link issue.
Host firewall LinuxWindows
iptables -L -n -vnetsh advfirewall show allprofiles
Rule out OS firewall before blaming the network.
Duplicate IP
arping -I eth0 <ip>
Two VMs with same static IP cause intermittent failures for both. Watch for multiple MAC replies.

✓ All 10 checks pass → move to Tier 2 | Any fail → fix here, do not proceed

Single VM affected→Start Tier 1 (OS config)

Multiple VMs, same port group→Skip to Tier 2 (VLAN)

All VMs on one host→Skip to Tier 4 (ESXi host)

Follows VM after vMotion→Tier 3 + Tier 4

Intermittent / flapping→Tier 3 (teaming) + Tier 5 (physical)

All clear, no traffic at all→Tier 6 (packet capture)