Suppose I have domain working https like https://www.example.com/ and my blog is working without https like http://blog.example.com/.
Is that wrong from SEO or Google point of view?
-
Its preferred for SEO to be behind https. And beyond SEO its good to keep people safe from MITM. Why don't you have an SSL on the blog too? You can use Cloudflare to get one for free (among other things) and it wouldn't affect your main domain if you didn't want CF layer on top. Or there is LetsEncrypt too that will be out of beta soon. – dhaupin Feb 13 '16 at 16:38
Since 2014, Google has been giving websites available over HTTPS a slightly higher search engine ranking score. Given that your blog is only available over HTTP, it may appear lower in the results for some searches. However, Google isn't penalizing web site owners if other parts of their web sites aren't available over HTTPS but the main site is, at least as far as we know.
Thus, not using HTTPS for your blog will only affect the ranking for your blog and not that of your main web site.
-
Nice answer. Two points. One, HTTPS is a TrustRank metric and only effects the SERPs as much as an up-tick in the sites trust score will. This is a minor effect, but real non-the-less since trust scores can effect the sort order of the SERPs. Two, the sub-domain is a separate site. Because the sub-domain and parent domain will be related within the index, the parent domain will positively effect the sub-domain and it is very likely that the sub-domain will not effect the parent domain unless the sub-domain is penalized in a severe way. Cheers!! – closetnoc Feb 11 '16 at 18:34
