Symptoms:
When you change the A record on your DNS server, you experience these symptoms:

• An ESXi 5.5 and later host continues to resolve the name associated with the changed A record to its old address.
• Investigation confirms the host in question is using the old address and the DNS server is resolving the name to its new address.
  

VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.5

This issue occurs when the ESXi host does not sync the change for a period of time after an IP address modification is done on the DNS server.

To reduce the number of DNS resolution requests having to traverse the network, the ESXi host DNS client maintains a DNS cache. If the ESXi host has already cached a resolved name and that IP address is changed on the DNS server, ESXi does not get notified of this change and the IP address is incorrect for a period of time.

To resolve this issue, clear the DNS cache on the ESXi 5.5 or later host.

To clear the DNS cache on the ESXi host, restart the nscd name server cache daemon:

Using Tech Support Mode in ESXi 4.1, ESXi 5.x, and ESXi 6.x
VMware ESXi 5.5 以降のホストにおける DNS キャッシュのクリア
清除 VMware ESXi 5.5 和更高版本主机中的 DNS 缓存