A content delivery network mainly helps sites with distant visitors, sudden traffic spikes or repeated attacks. A site whose customers are nearby gains less, so ask what it will fix before switching one on.

An upgrade in the renewal email

The hosting renewal arrives with an offer: switch on a content delivery network and make the site faster around the world. Speed tests sometimes recommend one too.

A content delivery network, usually shortened to CDN, keeps copies of a site's files on servers in many cities. Each visitor gets the files from whichever copy is nearest, instead of from your hosting server.

For a site with readers on several continents, that is a real improvement. For a plumber whose customers live within forty minutes of the shop, the question is what exactly it would fix.

What a CDN actually does

Most CDNs copy the files that are the same for every visitor: images, stylesheets, scripts and fonts. Some also store whole pages for a short time.

There are two common setups. In one, only the images and files come from a separate CDN address. In the other, the whole domain is routed through the CDN, which sits in front of your server.

The second kind changes where your domain points. That is why it can do more, and why it needs more care.

Where it genuinely helps

The second applies locally more often than owners expect. A spot on the evening news, or a post shared around a community group, can briefly send a small server more visitors than it was built for.

Why distance matters less locally

Distance adds a delay to every request a page makes. For a visitor in Australia loading a site hosted in Vancouver, each round trip takes a noticeable fraction of a second, and a page makes dozens of them.

For a visitor in Surrey loading the same site, the trip is already short. A CDN has very little distance left to remove.

It is worth knowing where your hosting server actually is. A server on another continent slows every page for local visitors, and a CDN only covers part of that gap.

What a CDN does not fix

Most slow small business sites are slow for reasons a CDN never touches.

A four-megabyte photograph is still four megabytes when it arrives from a nearby copy, and twenty plugin scripts are still twenty requests. A WordPress page the server builds slowly stays slow unless the CDN stores whole pages.

Fix the weight of the pages and the speed of the server first. A CDN then improves a site that is already reasonable, rather than disguising one that is not.

A worked example

A farm stay among the orchards of the Okanagan, with a farmhouse suite and two cabins, takes most of its summer bookings from Europe: families planning a Canadian holiday many months ahead.

Its site has large photographs of every room, a seasonal gallery of the farm, and a booking calendar from an outside service. The server is in Canada.

European visitors browse in their evening, the middle of the night here. Tests run from a European location showed the photo pages crawling, with most of the time spent waiting for images to cross the Atlantic.

The developer resized the photographs first, which helped every visitor. Then a CDN was set up for images, stylesheets and scripts only, with the booking pages and the contact form still loading directly from the server.

Before any change to where the domain pointed, the email records were copied and checked line by line. The setup, the account and its login were written into the site's documentation.

Local guests noticed nothing, as expected. The photographs now reach European families from a copy on their own side of the ocean, which was the whole point.

What to ask first

Ask what problem it should solve, in one sentence. Distant visitors, spikes and attacks are good answers; faster in general is not.

Ask what will be stored and what will not. Contact forms, booking pages, shopping carts, logins and anything personal should never be cached and handed to the next visitor.

Ask how changes get through. A stored copy of an old page can keep appearing after you edit it, until the copy expires or someone clears it.

And if the whole domain will run through it, ask whether any security software blocks visitors by address, since the server will see the CDN's addresses instead of theirs unless told otherwise.

Do not lose the email records

Routing the whole domain through a CDN usually means moving the domain's DNS records, the settings that say where the website and the email live, to the CDN's own systems.

If the email records are not copied exactly, mail stops arriving, and it can be a day before anyone notices. The quote requests sent that day never reach you.

Export the existing records and compare them before the switch, then test every important mailbox afterwards.

One more company in the chain

Last month a cloud storage outage in the United States took images, forms and whole sites offline for hours.

A CDN is the same kind of dependency. Working well, it adds resilience. Failing or misconfigured, it can take the site down even while your hosting server is fine.

Make sure whoever manages the site can bypass the CDN quickly and serve the site directly if something goes wrong.

The counter-case

A CDN can make sense for a local business. A tourism operator, an event with a ticket rush, a shop with a big seasonal sale, or a site that has been attacked repeatedly all have good reasons.

Many hosting plans now include one at little or no cost, and with a careful setup and someone responsible for it, there is little harm in using it.

The case against is not the technology. It is switching it on without knowing what it fixes, what it stores, and who looks after it.

Ask what it is for, check what it touches, and keep the setup written down.

Before switching it on

  1. Write down the problem it should solve.
  2. Fix image weight and server speed first.
  3. Check where your visitors actually are.
  4. Exclude forms, carts and logins from caching.
  5. Copy and test the email records before switching.
  6. Record the account and who manages it.
  7. Know how to bypass it in a hurry.

Step five is the one that most often goes wrong. A slower site is an inconvenience, while a day of quote requests that never arrive is lost work.

Listing every outside service the site already relies on is covered in parts of your site that live on someone else's servers.

Frequently asked questions

What is a content delivery network?

A service that keeps copies of a site's files on servers in many cities, so each visitor gets them from a nearby copy instead of the hosting server.

Does a local business site need one?

Often not for speed, since local visitors are already close to the server. It can still help with traffic spikes, repeated attacks or visitors from overseas.

Will a CDN fix a slow website?

Rarely on its own. Oversized images, too many scripts and a slow server stay slow. Fix those first, and a CDN then improves a site that is already reasonable.

What can go wrong when switching one on?

Email records lost when the domain settings move, forms or carts stored and shown to the wrong visitor, and edits that do not appear until old copies expire.

What should never be cached?

Contact forms, booking pages, shopping carts, account logins and anything personal. Those must come straight from the server, fresh for each visitor.

Who should look after the CDN?

Whoever manages the site. The account, login and setup should be written down, along with how to bypass the CDN quickly if something goes wrong.

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.

Offered a CDN with your hosting renewal?

Forward the offer along with your site address, and we will explain what it would change and what to check.

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