WHAT IS HOST-IT DNS FAILOVER™? DNS Failover monitors your server, and if it’s unavailable for a certain period of time, it will dynamically update your DNS records accordingly so that your domain name points to an available server instead. This allows you to have a backup site in a separate data center that can be automatically assigned to your domain if the server you host your website on is unavailable. Usually, the software is set to check every three minutes (to allow reboots) and send an email warning and then, after a second check, three minutes later, change the DNS records automatically. However, this setting can be changed to anything between one and sixty minutes. NB: If your website writes data to a back-end database, it would be unwise to link the backup site to an exact copy of your main site, otherwise the data will not be synchronized (the same would apply to email), however, instead of displaying a blank page, This will allow you to have a maintenance page or have your developers design a static/basic version of your site. which can be seen if your main site is unavailable. Note that if you want real-time replication of the data to provide full failover for mission-critical solutions, we can also offer this through dedicated servers, however the cost will be substantially higher, so the above is a more basic version of this, but still useful to have in place as a backup.
WHAT DOES HOST-IT DNS FAILOVER CHECK?™ It will check almost all types of TCP/IP services, for example, the website and email availability (i.e. HTTP, SMTP, IMAP, POP3, FTP, etc.). Please note that, unlike our application availability monitoring, this will not verify that an individual web page is working, only that the server itself is responding to the port you select to check (i.e. the entire server/service is down).
HOW DOES IT WORK? Availability is checked every two minutes, and in case your primary server is unavailable for X minutes, it will send an instruction to your DNS servers (subject to your DNS provider allowing it) to update the IP address to the backup address you designate. This is done through the DNS protocol (and you can use encrypted signatures for security if necessary) or through WMI or through HTTP dynamic updates.
The failover server will also send you email notifications to notify you of any unavailability.
Please note that our price also includes the use of our own DNS servers if you wish (recommended).
WILL FAILOVER WORK INSTANTLY AND ALSO FOR ALL USERS? Part of the configuration involves reducing the TTL (Time to Live) on domain name servers to five minutes. Although TTL can be reduced to 2 minutes, this is the minimum recommended time to ensure that providers who meet the normal TTL minimums do not ignore the entire request.
When you access a website, you use a resolver to convert the DNS into a destination IP address for your site. If no user has accessed your site within the period of your TTL from this resolver*, as soon as the failover server changes your site’s IP, the backup site will be visible. If someone using the same resolver* has just accessed your site, it may take up to ten minutes to view the backup site, but after this period, the backup site will be automatically viewable.
Once the service is restored, our failover server will automatically detect that the server is backed up and reverse the process.
* This depends on your provider meeting the lowest TTL settings (most do) and those that typically don’t have a minimum of two hours.
IS THIS A PERFECT/PERFECT SOLUTION? Nope. This is a very useful addition for your peace of mind, however, it has limitations in the sense that failover will not be perfect and failback will take the same time. It also means that services of a dynamic nature will also have to have separate replication/failover/failback functionality if you want to fail over to live services, making it better suited for services or websites that can run independently.
The following scenarios are examples of the best use of this technology
1. Important static sites.
2. Automatic backup or basic/static site maintenance page for a dynamic primary site.
3. Back up the SMTP site so that if your SMTP gateway is down, users can be automatically routed to a backup gateway within minutes so they can continue sending emails.
WHAT ELSE IS NEEDED? You will also need to register for accommodation at the backup location. We can offer this in our own primary data centres in Northampton or if they are already hosted with us in Bletchley, Manchester or in the US at a discount on our normal plans with reduced bandwidth).
HOW MUCH DOES THE DNS FAILOVER SERVICE COST? £75 + VAT set up and £2 + VAT per month for the first domain and 0.50p + VAT for any additional domains.
HOW DO WE ORDER THIS? Go here to order the service. Alternatively, if you need something customized, please contact us.