Just use the DHCP mode ,it is OK.
You do not need to appoint the specific DNS server unless the IAMMETER cloud IP can not be resolved(Normally, it is very low possibilities).
Keep the DNS record can be synchronized to all DNS servers around the world is the work of the DNS service we used
I don't think you understood the question.
I assign a local LAN DNS server to all my network clients by setting the "DNS Server" client option in my DHCP setup. Does the Iammeter device use the DHCP-assigned DNS server, or is it hard-coded to use a specific DNS service? I ask because the DNS server IP address in use is not shown in the Iammeter interface.
it use DHCP-assigned DNS server.
to get the DNS server IP.