Unable to Obtain a DHCP Lease on Interface VMK#

Products

• VMware vCenter Server

Issue/Introduction

• The ESXi host displays an error or alarm: Unable to obtain a DHCP lease on interface vmk2.
• The VMkernel interface (vmk2) fails to acquire a dynamic IP address and may fall back to an APIPA address in the 169.254.#.# range APIPA IP addresses (169.254.#.#) seen on vmk10 and vmk11 interfaces.
• Services relying on that interface (e.g., NFS storage, vMotion, or Management) experience connectivity loss or outages.
• The vobd.log at /var/log/ contain entries such as:
  • [esx.problem.dhclient.lease.none] Unable to obtain a DHCP lease on interface vmkX
  • [vob.user.dhclient.lease.none] Could not get a lease on interface vmkX

Cause

This issue occurs when the DHCP DORA (Discover, Offer, Request, Acknowledge) process fails between the ESXi host and the DHCP server How to troubleshoot DHCP issues?. Common triggers include:

• Network Reachability: Physical network outages or VLAN configuration errors preventing the host from reaching the DHCP server.
• Firewall Blocks: UDP ports 67 (Server) and 68 (Client) being blocked by physical firewalls, network ACLs, or the ESXi built-in firewall.
• DHCP Server Configuration: The DHCP server is out of available IP addresses, or it is not providing the mandatory Option 51 (Lease Time) in its response.
• Lease Renewal Failure: A network outage occurring during the DHCP renewal window (T1/T2) that lasts longer than the remaining lease time.

Resolution

1. Verify Logs and Error Patterns

Review the following logs on the affected ESXi host to confirm the DHCP failure:

• dhclient.log: Look for No DHCPOFFERS received or repeated DHCPREQUEST attempts without an acknowledgment NSX host TEP (vmk) interfaces do not receive dynamic IPs from DHCP Server.
• vobd.log: Check for vob.user.dhclient.lease.none events.

2. Validate Network Connectivity

• Ensure the physical uplinks (vmnics) associated with the vSwitch/Port Group for vmk2 are "Up" and configured for the correct VLAN.
• Confirm if the ESXi host can ping the DHCP server or its gateway.
• Verify that an IP Helper (DHCP Relay) is correctly configured on the Top-of-Rack (ToR) switch if the DHCP server is on a different subnet NSX Faulty TEP while using DHCP.

3. Check Firewall Rules

Ensure that UDP ports 67 and 68 are permitted across the entire data path, including the physical network infrastructure and any software firewalls.

4. Perform Packet Captures

Use the pktcap-uw tool on the ESXi host to determine if DHCP Discover packets are leaving the host and if Offer packets are returning:

pktcap-uw --uplink <vmnic_name> --capture UplinkSndKernel,UplinkRcvKernel --ip --udpport 67 -o - | tcpdump-uw -ner -

• If only Discover packets are seen leaving the host but no Offer returns, the issue is in the physical network or DHCP server How to troubleshoot DHCP issues?.

5. Interface Reset

If the interface is stuck without an IP, attempt to reset the physical link to trigger a new DHCP request:

esxcli network nic down -n vmnic#
esxcli network nic up -n vmnic#

 

6. Recommended Best Practice

For critical infrastructure traffic such as NFS storage or Host Management, it is highly recommended to use Static IP addresses instead of DHCP to prevent service disruptions during network or DHCP server failures APIPA IP addresses (169.254.#.#) seen on vmk10 and vmk11 interfaces.