5 replies to this topic

[madams]

Hi

I am trying to improve my sites render time in browser by sending images from a sub-domain in paralel...

www.images.mysite.com

I have asked my host to create 4 sub-domains

images.mysite.com

js.mysite.com

css.mysite.com

resources.mysite.com

This is to serve these files for quicker download.

My host reply was "Sure, Please provide A or CNAME records where you'd like them pointed.

I am not sure where, or understand the question.

I have my site setup in Webmaster tools with the www. (not sure if this helps)

What do they mean by this. I have searched for the info but all I could understand was to point non www. to www.

Can anyone shed some light on this for me.

I want to load my website page and have the images come from...
Images.mysite.com

Not

mysite.com/red/images

Thanks

[cfreek]

It sounds like the want the DNS records' information. Do you have the hosting accounts for the subdomains set up yet, or is that what you want them to do?

If it's what you want them to do, you may want to clarify that with them.

Edited by cfreek, 03 October 2012 - 12:22 PM.

[Jill]

I don't have an answer to your question, but I do wonder why you think having your images on a subdomain will load them any faster than simply having them on the main domain.

[Ron Carnell]

Jill, a browser will only open two concurrent "streams" at a time to the same hostname (HTTP 1.1, section 8.1.4). If you have three images, it will download two of them simultaneously, but it won't even start the third until one of the others is completed. Throw in the HTML, the CSS, the JavaScript, yada yada, and the two stream limitation becomes a serious bottleneck. Moving some of those files to different domains means the browser can open more streams at a time and on a high bandwidth client that can make a significant difference.

Here's a more in-depth https://developers.g...elizeDownloads'>guide directly from Google.

There are, of course, trade-offs, Madams (there are always trade-offs).

When a browser wants to connect to images.mysite.com, it first has to request a DNS lookup. Somewhere out there in cyber space, a DNS server will have a record that ties the domain name to a specific IP address (that's exactly what the A or CNAME records do). Our trade-off exists because the DNS lookup takes time, too, and it can sometimes eat up any savings you might have garnered by using multiple domains. In short, using multiple domains to serve your assets is a good strategy. Using too many domains, however, is not. In my opinion, four is probably too many, and in any event, you certainly don't want to incur a DNS lookup for just one CSS file or just one JS file (and combining multiple CSS / JS should be your first goal in speeding up browser rendering).

Unfortunately, there's no easy answer to your question because it depends so much on how you are being hosted.

If your host is not also your DNS provider, you'll have to get your DNS provider involved (your host needs an IP address to assign to the domains). Eventually, that IP address has to point to a spot on a hard disk somewhere where the images and CSS files will be stored. That can be a subdirectory in the main domain, it can be another ROOT dir somewhere on the same web server, or it can be on an entirely different machine (or even a dozen different machines; I use Amazon Web Services to serve images from a sub-domain that exists on their network -- something perhaps to consider).

Although it's a very different scenario (assigning a domain to a blogger account), Google has been kind enough to provide instructions for setting up a CNAME for some of the more popular hosting packages. Honestly, though, you probably won't need a CNAME. An A record, which just consists of an IP address, is the more likely alternative. Again, though, it ultimately depends on your hosting package.

In short, Madams, the only ones who can answer your question specifically are the people who asked it: your host. They'll have to tell you what you need to provide them in order to create the subdomains.

[madams]

Thanks Guys

Hi Ron. The problem is, I don't even know what to tell or ask my host. I thought the sub-domain would be like my main domain and I could chuck the images in there and change the links from my old images to the new ones and that was that.

Maybe I will hold my hands up and tell my host I am lost. Trouble is, they tell me often (host), they dont get into site-development and because of this I wanted to read up on it and understand about A and Cname records but cant find info that suits my needs.

The other thing, my host does not have CPanel, or similar, this allows people to set-up their own sub-domains and configure them. So it cant be Rocket Science!

I want to understand.....

[chrishirst]

You don't ACTUALLY need any subdomains to exist physically to allow parallel HTTP requests to be made, you only need them to resolve to the same document root as domain.tld does, in fact you could leave the "www" off your image URIs and have TWO parallel request routes without doing anything at all.