old ASP.NET: rotate/shuffle/randomize a variable for each pageview or each user by ipv4

We try to hotfix an old ASP.NET project. only got PHP experience yet. Instead of the below, the ‘Key’ needs to be randomly selected from a list so that each “key” is used about equally often. string sKey = ConfigurationManager.AppSettings[“Key”]; (Referring to the web.config file.) For example 10000 people use the site per day, 20000…