When should I use or avoid subdomains?

Question

Recently, a user told me to avoid subdomains when I can. I remember how to read google treats subdomains as a unique site (is that true?). What else happens when I use a subdomain, and when should I use or not use a subdomain?

I heard that cookies are not shared between subdomains? I know that 2 images can be DL simultaneously from the site. Will I have DL 4 if I use sub1.mysite.com and sub2.mysite.com?

What else should I know?

Answer 1

You can share cookies between subdomains, provided that you set the correct parameters in the cookie. By default, they will not be shared.

Yes, you can get more simultaneous downloads if you store images in different subdomains. However, the other side of the scale is that the user spends more time resolving the DNS, so it is impractical to have, say, 25 subdomains to get 50 simultaneous downloads.

Another thing that happens with subdomains is that AJAX requests will not work without any effort (you MAY make them work with document.domain tricks, but this is far from easy).

It is not possible to help with part of SEO, however, although some people interfere with both yoursite.com and www.yoursite.com and return the same content because it "dilutes your pagerank". Not sure how true this is.

Answer 2

You complicate a lot of things. Statistics collection, spider management, html5, XSS storage, interframe communication, virtual host configuration, third-party advertising, interaction with remote APIs, for example google maps.

Not to say that these things cannot be resolved, simply that increasing complexity adds more work and may not provide suitable benefits for compensation.

I have to add that I went this way once for an ad site by adding domains like porshe.site.com, ferrari.site.com, hoping to increase the ranking for these keywords. In the end, I did not see a noticeable improvement, and even worse, Google walked across the site through each subdomain, which means that searching for ferraris can return porsche.site.com/ferraris instead of ferrari.site.com/ferraris. In short, Google believed that every site duplicates, but it still crawls every site every time it visits.

Again, workarounds existed, but I chose simplicity, and I do not regret it.

Answer 3

If you use subdomains to store images of websites, javascript, style sheets, etc., then your pages can load faster. Browsers limit the number of simultaneous connections to each domain name. The more subdomains you use, the more connection can be made to collect the contents of web pages.

Answer 4

Recently, a user told me to avoid subdomains when I can. I remember how to read google treats subdomains as a unique site (is that true?). What else happens when I use a subdomain, and when should I use or not use a subdomain?

The last thing I heard about Google optimization is that domains account for more pagerank than subdomains. I also believe that page ranking calculations are for one page, not for a site (according to an algorithm, etc.). Although the only person who can really tell you is a Google employee.

I heard that cookies are not shared between subdomains?

You should be able to use cookies for all subdomains. www.mysite.com sub1.mysite.com sub2.mysite.com may use the same cookies, but the cookie specified for mysite.com cannot be provided to them.

I know that 2 images can be DL simultaneously from the site. Will I have DL 4 if I use sub1.mysite.com and sub2.mysite.com?

I'm not sure what you mean by DL at the same time. Often a browser with a single thread downloads images one at a time, even from different domains. Browsers with multiple stream configurations can simultaneously load multiple items from different domains.