Affected Products : VMware vSphere ESXi (6.x 7.x & 8.x)
Issue Summary
In a specific cluster ESXi hosts showing up as “Not Responding” or “Disconnected” in your vCenter Server.
While reconnecting it shows error “Host IP address conflict detected”
In vCenter /var/log/vmware/vpxd/vpxd.log looks like:
Warning vpxd[07289] [Originator@6876 sub=InvtHostCnx
opID=HeartbeatStartHandler-460059d8] Host IP address conflict detected. [vim.HostSystem:hostname.net]
is trying to change IP from hostname.net to xx.xx.xx.xx New IP is already used
by hostname.net
2025-04-11T07:54:40.478Z info vpxd[07287] [Originator@6876
sub=vpxLro opID=lro-31224504-1ecae696] [VpxLRO] — BEGIN lro-31224504 — — HostDisconnectLRO
— 2025-04-11T07:54:40.488Z warning vpxd[07305] [Originator@6876
sub=IO.Connection opID=lro-31224504-1ecae696] Failed to resolve address;
<resolver p:0x00007f9e9824d110, hostname.net:443‘, next:(null)>, e:
1(Host not found (authoritative)), async: true, duration: 8msec
2025-04-11T07:54:40.488Z warning vpxd[07305] [Originator@6876
sub=HttpConnectionPool-000000 opID=lro-31224504-1ecae696] Failed to get pooled
connection; <cs p:00007f9ea4256220, TCP:s70t0038h.apj.dxccorp.net:443>,
(null), duration: 9msec, N7Vmacore15SystemExceptionE
(Host not found
(authoritative)) –>
Note : The logs shown may different and not similar
Most probably this issue occurs when esxi host added in vcenter with hostname and due to some DNS issue not able to resolve name to ip and ip to name .
Cause:
ESXi host is trying to change its IP address to one that’s already in use however the IP it’s trying to change to is already assigned to itself
vCenter detected that the host “esxihostname.net” is now reporting it’s IP instead of FQDN.
Consequence of the DNS failure. vCenter cannot establish a connection to the host using its FQDN because it can’t find the corresponding IP
This indicates that the vCenter server cannot resolve the hostname to an IP address using its configured DNS name.
As a result, vCenter initiates the process to disconnect the host.
Try following checks to confirm the cause of issue.
Check problematic esxi hosts can access esxi web client with name and ip
From the ESXi Host (SSH)
Try to nslookup and reverse lookup vcenter hostname from esxi (nslookup vcenter name and nslookup vcenter ip)
From the vCenter Server (SSH)
Try to nslookup and reverse lookup impacted esxi host fqdn and ip address
nslookup esxi host FQDN and esxi host IP address
Check if vCenter and problematic esxi hosts can resolve name to ip and ip to name
Check if you can ping esxi management ip address and fqdn from vcenter
Resolution:
If you can’t resolve the name to ip and ip to name and can’t ping esxi from vcenter nor able to access esxi web client with FQDN e.g., “https://esxihostfqdn.net”, however it can access through
IP address. Then this confirms to be the DNS issue, reach out to your DNS team if you don’t manage the DNS servers and check impacted ESXi host A record and PTR record.
Once the DNS entries are fixed try reconnecting the esxi host to the vCenter. It will connect like a charm.
