Site load time is a ranking factor, so a CDN that speeds up load time should be good for your SEO, right?
Alright, first a little background.
A CDN, or Content Delivery Network, is a network of servers deployed in data centers across the world. Why? To deliver content to users more quickly by connecting them to a server that is close by and/or not under heavy load. Using a CDN can boost your site's load time and protect you from DDoS attacks, and that's all great.
Google employees have also publicly said that fast site load time can improve your rankings, so isn't that the end of it?
Here's why a CDN isn't always going to be beneficial for your SEO.
How a CDN Could Hurt Your SEO
Let's start with this: page load time isn't some amazing ranking signal that is going to propel you in front of everybody. It counts for SEO, yes, and it's certainly good for the user experience, but it has only a very minor impact on rankings.
While site speed is a new signal, it doesn't carry as much weight as the relevance of a page. Currently, fewer than 1% of search queries are affected by the site speed signal in our implementation...
That comes from a post on the Google Webmaster Central blog posted by Amit Singhal and Matt Cutts. It doesn't get much more clear cut then that. Compare that to Panda 4.0, which impacts 7.5 percent of queries. It's starting to look like site speed isn't actually that big of a deal, isn't it?
Now for the actual damage a CDN can do.
Here's what Jon Hyman, a co-founder of Appboy, had to say about CloudFlare, at least back in 2012:
Appboy is going to cancel our Pro CloudFlare account and leave the service. CloudFlare has a great feature set, but their uptime track record has been awful.
Ouch. That's the thing about using a service that must constantly grow to keep up with expanding resources, not to mention gets used by many to block DDoS attacks. If the resources can't keep up, you're going to get downtime. And downtime isn't just bad for the user experience, it's bad for your SEO.
Here's what Matt Cutts has said about site downtime:
"If your website is down for a relatively small amount of time, you know, a day or two, then just bringing it back up should mean that it pops right back into the search results, or it won't disappear at all. But at the point where your website is down for several days, or a week, or a month, then yeah, we probably are going to drop it from the search results..."
So, why am I emphasizing "it pops right back into the search results?" Because that means that if Google attempts to crawl your site and it's down, it might take your site out of the search results until the next time you get crawled, which isn't always all that timely.
While a well optimized site should get crawled dozens or hundreds of times per day, individual pages often get crawled only once per day or less, even on a well optimized site. Unoptimized pages can go weeks without seeing Googlebot. If Google sees that a page is down, this could mean that the page will be dropped from the search results for days, weeks, or more.
So, Should You Use a CDN?
The answer is, if your site is having load time issues, and if the improvement in user experience alone is worth it, then yes, you should use a CDN.
You should use a CDN that has a great track record and, just as importantly, a Service-Level Agreement with guaranteed uptime.
And if the only reason you want a CDN is because you think it's going to improve your SEO, I'd say you shouldn't bother. If load time isn't hurting the user experience, it's probably not hurting your SEO, so you'll just be wasting your money.
Image credit: reynermedia