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CNAME/ANAME Failover

    CNAME/ANAME failover is conceptually the same as A record failover but with the flexibility of aliases, allowing for more elaborate and reliable configurations and monitoring services. Setting up CNAME and ANAME failover is the exact same process so for this tutorial we will focus on CNAME. For more information on CNAME and ANAME records, click here. 


Here are the steps to get started:


First, you want to log into the Constellix control panel through the Sonar application. If you are already logged into another Constellix application, use the menu button in the top left corner to switch to the Sonar application. 

From the dashboard, click Add Check and choose the kind of check you want to create. There are four different kinds of checks you can create: web, TCP, DNS and RUM. In this example, we will create a web check to monitor the IP addresses of our web servers.

Name: Make sure you use a really specific name for your checks. For example, if we want to create a check for a web server in Europe, we might want to name it EU Web Server. This comes in handy later when you start applying lots of checks to your DNS records. 

Host: Specify the FQDN for your check.

You’ll notice there are a lot of options when you configure a check. We’ll break them down for you quickly.

Intervals

Interval: Choose how often you want our monitoring nodes to check the status of your endpoint. Keep in mind, if you choose a shorter time, the more costly it will be. Also consider that the more monitoring locations you choose will reduce the interval time if you choose the “Once per Site” or “Once per Region” interval policies. Since we are running checks from multiple locations each interval, the interval period is actually reduced to Interval/Monitoring Locations and can be as short as a fraction of a second.

If you are worried about cost, try out our pricing calculator.

Interval Policy: You can choose Simultaneous (all locations each check) or Once per Site. What these mean is how many locations will be checks at each monitoring interval.

Verification Policy: If you choose more than one monitoring location, you can choose how a system is determined to be “unavailable”.

Simple

If one location is chosen and is down then the check will be considered down. If multiple, then next closest location is checked. If both are down, then down.

Majority

Half or more of the locations have detected the endpoint as down.

Notification Report

Choose the expiration of the notification report. This report is included with email alerts when a check is down and shows a detailed traceroute and recent downtime for the check.

Testing

When you are done, make sure you test the check by clicking the Test Check button and a monitoring location from the dropdown menu.

Testing a monitoring check in Constellix Sonar

Save your check. 

Repeat the above steps for each CNAME record that you wish to include for the failover setup.

Now that your Sonar checks are setup, go back to the control panel to create the failover record.

1.Select Managed DNS and click on Domains


2. Select the Domain Name you want to add a CNAME failover record to.


3. Under the CNAME Records section, click the plus_iconto add a record.


4. In the following screen, you will add the record information.


A) Name: This will be the hostname for your record. It is important to note, the domain name is automatically appended to the “Name” field of the record. Note the name field is required, because a CNAME record can not be defined for the root record of the domain.

B) TTL: Edit the TTL. Time to Live is measured in seconds and is the amount of time the record will cache in resolving name servers and web browsers. Please note that a lower TTL in any failover setup is preferred as the cached record in the resolver will update sooner allowing for less of a delay in redirected resolution. 

C) Record Mode: The Record Mode will be switched to Failover for this tutorial. 

D) Host: Once Failover is selected under Record Mode, a new window will populate below. Enter the FQDNs that you previously created checks for into the boxes below “Host”. If you have more than two, click the “+ Add Another Host” button to populate more fields.

E) Sonar Check:  Click the fields below the word “Sonar Check” and select from the drop down menu or type in the name of the specific checks you created that correspond with the FQDNs in the setup.

Click Save And Close at the bottom of the window and then, as with all changes in the account, go to the top of the page and “click here” to review and apply changes. Click the green Commit Changes button and you’re all set!













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