in order to prevent duplecate contents on your blog. you always should no index blog archives and tags.
no one want to get punished by those things that he never did in their life.
if you always write unique and quality contents on your blog, you will never want search engins to punished you like a spammer.
if you don’t have no index blog archives and tags then it’s mean you’re inviting search engins to penalize you for running the blog with duplicate contents.
How your contents are considered duplicate?
this is a reall question that you might be asking after reading the statement above.
well, your contents are considered duplicate because when someone search a keyword on search engins, they will see your categories and tags. some of your categories would show a random excerpts if you don’t have hand written excerpt for each category and tags on your blog.
when search engins will notice the same excerpt for two or more URLs on your blog, they will think that you are writing a single content many time.
search engins strongly hate this practice therefore they will decide to decrease the ranking of your blog or website.
if you have hand written excerpt for each tag and category on your blog, you would not get a big punishment, but I believe no one follow this practice.
if you are running wordpress as your content management system, it’s easy to set no index blog archives with the use of a wordpress plugin.
all is you need to install and configure yoast seo plugin with your wordpress blog, and this will allow you to set no index blog archives, tags, pages and posts.
after the installation of yoast seo, head over to titles and metas page, click on taxonomies tab and check the noindex radio button for categories and tags.
have you any other recommendation to set noindex attribute to your wordpress posts, pages, categories and tags? please share the method that you follow in comments below.