VMware recommends that you use static IP addresses for ESX/ESXi hosts. During host upgrade, static IP addresses are a requirement.

DHCP IP addresses can be problematic during host upgrades. Suppose, for example, a host loses its DHCP IP address during the upgrade because the lease period configured on the DHCP server expires. The host upgrade tool that you are using (either vCenter Update Manager or vSphere Host Update Utility) would lose connectivity to the host. The host upgrade might be successful, but the upgrade tool would report the upgrade as failed, because the tool would be unable to connect to the host. To prevent this scenario, use static IP addresses for your hosts.