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 cause problems 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 (for example, vCenter Update Manager) 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.