Global wildcard redirect

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Michael Martinez: I think in this scenario I would set everything to "noindex". It doesn`t sound like there would be appropriate alternative content to redirect to.
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  Neil Cheesman: Thanks Michael - you are correct in there wouldn`t be a like for like redirect - how and where would I set this sub-domain to no-index?
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  Michael Martinez: Neil Cheesman I would just update every page to use the tag.
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  Neil Cheesman: the urls don`t exist as `populated` via cname - I have added a robots.txt to the sub-domain
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  Michael Martinez: Neil Cheesman Well, the "robots.txt" won`t do anything but block crawlers. I`d remove that. You could install WordPress on the site and set it to noindex everything. They no longer block crawlers. Now in SETTINGS >> READING you just check "Discourage search engines from indexing this site". That will generate a "soft 404" page with a "noindex".
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  Neil Cheesman: the sub-domain was populated via a supplier and that agreement ended a couple of days ago - and now the sub-domain`s content is `defunct`. several hundred urls.
  The main domain has Wordpress... are you suggesting installing Wordpress within that sub-domain?
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  Michael Martinez: Neil Cheesman Yes. As long as you control the subdomain and can install whatever you want on it, you can set up a blog and use it to noindex all unknown URLs. You could also try removing the subdomain in Search Console with the URL removal tool - I think that is still there. But that only works for Google. If the subdomain gets traffic from Bing or Bing partners then the problem persists. So I think setting up a default "noindex" is the best way to go. You`ll have to upgrade the WordPress every time a major change is released but it will upgrade itself for basic security.
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  Rituraj Shrivastava: I would do a wild card redirect just because if there is any link equity in any of those urls that will pass along to your homepage.