The style guide doesn't like wildcard, it requires a list of subdomains with a plain rewrite rule in rulesets rather than regexes with long strings of subdomains.

However, some sites have a bunch of subdomains to balance loading pressure, or just to avoid concurrent connections limit in bowsers. Then it is too much to list them all.

A recent example is #6899, in that case we have c[2-79].yunpan.360.cn, which have exactly the same function. There are 3 options:

1. List nearly 80 subdomains one by one, which is a huge list.
2. Use a wildcard with a special rule, but then we have to use regexes with long strings of subdomains instead of a plain rewrite rule.
3. Use a exclusion with negative lookahead operator, which is confusing for somebody.

The style guide notes option 2 and 3 as a bad example, even though option 1 is not an elegant solution. If this still need to consider, another example is McAfee.xml:

Only some certain pages under www.mcafee.com have https, and all of the others redirect to http. In this case we don't have option 1, so it seems to be a problem that has no solution if we don't violate the style guide.