One domain 2 IPs

Our web host hasn't set up WPMU before and we'd like to if their assumptions are correct. See below.

We are setting up WPMU on a separate LAMP VPS. The domain is already in use but we'd like to use it for the blog network to. Any advice on the 'safest' most practical way to do this would be appreciated.

WebHost: "Assuming we buff the VPS that the host name is culture360.org (the actual one is still with 116.12.53.2) and administrate the WPMU using IP (for example 116.12.51.123, meaning we can set the installation as a default site and exclusive to this IP, we can assume every of this project you create will name after culture360.org

for example
a.culture360.org 116.12.51.123
b.culture360.org 116.12.51.123
c.culture360.org 116.12.51.123

with all these done up on the DNS record to the the config file on the httpd, logically it will work. Just that there'll be a manual entry to be done everytime you are creating one project as it's UNSAFE to create a wildcard dns record for this domain I assume."