Configuring DNS Failover For A Records: DNS Made Easy Tutorials

Uploaded by DNSMadeEasy on 20.12.2011

In this tutorial we will discuss how to configure DNS Failover and System Monitoring settings
for A records within the DNS Made Easy control panel.
System Monitoring in DNS Made Easy detects the reachability of your internet services based on your monitoring criteria.
DNS Made Easy will check the reachability of your services roughly every 2 minutes from multiple points of presence-or PoPs, worldwide.
If multiple PoPs are unable to reach your services,
downtime has been detected, and we will notify you using the contact info you have provided.
DNS Failover in DNS Made Easy combines the power of our System Monitoring services with our industry leading DNS services.
If System Monitoring detects a system that’s down, it will check for possible replacement servers from a pre-determined list you provide.
Once a functioning backup system is detected, DNS Failover triggers our Peregrine Instant DNS update technology
to update our name servers worldwide with the backup system’s IP.
Our system monitoring services will always verify that the secondary IP address is online
and functioning according to your monitoring criteria before any DNS change is made.
This way, traffic is not migrated to an unavailable, or malfunctioning system.
The next time anyone asks for DNS resolution of your fully qualified domain name-or FQDN,
they will be given the IP of your up and running system.
DNS Failover is a simple way for companies to utilize their disaster recovery facilities, and help prevent possible downtime.
System Monitoring services will continue to monitor your primary IP address until it is detected back online.
You can configure the DNS Failover services to immediately change your DNS back to the original system
or you can choose to manually change the DNS yourself at your own convenience.
Configuring DNS Failover and System Monitoring for A records in DNS Made Easy is a very simple process.
First, click on Managed DNS under the DNS tab in the main menu.
If you have recently modified the domain you want to work with, you can choose it from the Recently Updated Domains list.
If your domain is not listed, you can start entering your domain name in the Managed DNS search box.
Once you enter the first few characters of your domain name into the search box,
a matching list of domain names will appear for you to choose from.
You can also enter your full domain name and press the enter key.
In this example we will be working with the domain,
Once your domain is loaded in the control panel, select the Records tab if it is not already the active tab.
The Records tab provides an easy to view grid layout for all of your record types.
Click on the appropriate row under the System Monitoring/DNS Failover column to enter your advanced configuration options.
The A record we will configure System Monitoring and DNS Failover for is already created within the domain.
If you are unsure of how to create an A record, please watch the tutorial video Working with A Records.
A listing of all of our tutorials can be found at
In this example we will activate the DNS Failover and System Monitoring service for the website,
We will indicate that our primary IP is found at
and our backup IP is found at
We will want to monitor the HTTP service over port 80.
To be more specific, we will also include in this configuration additional monitoring criteria.
Specify that you want to check for system_status.php and verify that it contains the string UP.
Turn on the Monitoring Notifications checkbox.
This enables you to receive emails from DNS Made Easy in the event there is a change in your system status.
The System Description text box contains a description of the host to be monitored.
This will be included in the system monitoring notification email we send you, to let you know which host has been affected.
In this box, enter web server.
The Notification Conact dropbox allows you to choose which contact list receives the monitoring service’s notifications.
If you do not have a contact list already defined, click on the pencil icon to the right of the drop down box to create one.
For this example, choose the NOC List.
The Maximum Number of Emails field allows you to limit of how many emails you receive from the System Monitoring service.
We will always send you an email when the systems are first detected down and when they are back up again.
Please note: We will also send you an email for every 5 consectitive failures.
If your system is down for multiple hours it can result in you receiving hundreds of notification emails, so make certain you set the limit to five.
The Sensitivity setting allows you to specify how many checks you’d like DNS Made Easy to perform on your service.
High sensitivy will set fewer checks and low sensitivity will set more checks.
Note: The more checks you require DNS Made Easy to make, the slower detection of a failure will be.
All checks are run in sequence, so it will not wait for any specific time period before it retries.
For this example we will set the sensitivity to Medium.
The list of possible protocols to check are HTTP, HTTPS, TCP, UDP, and DNS.
Each protocol gives you different options for monitoring.
TCP just gives you the port to check.
UDP allows you to specify the port and a string to pass to the server and a timeout.
DNS allows you to specify the record to query and a timeout.
HTTP and HTTPS give you the most options.
The HTTP and HTTPS checks always confirm that we receive a successful 200 level response code from your web or application server.
Optionally, the HTTP and HTTPS checks allow you to specifiy additional parameters such as a a path to query,
and can also check for a possible string as well.
In this example you will check the HTTP protocol. Once the protocol is set for HTTP, additional options will appear.
The Port to Monitor field, allows us to specify the exact port that we will ask the server for.
We will use the HTTP default port of 80.
Since we are using an HTTP check in this example, we can also specify the FQDN that will be accessed.
The FQDN is passed in the HTTP request header. This can be important if you are doing virtual hosts within your web server.
Ask your web and system administrator if this is important for your check.
Since our webserver does do virtual web hosting you want to make sure that the correct domain is being tested.
Enter in the FQDN field.
If this field is left blank, the system monitor will query your webserver by IP address only.
In the File to query field, specify the system_status.php script that we have written.
In String to Query for, we will enter the string UP.
The script that we have written will output UP if everything is working properly.
Note: It is important to know that DNS Made Easy will only search the first 2 KB of text that is returned.
Check the DNS Failover checkbox. Left unchecked, no failover event will occur, and you will only receive our notification emails.
Since we actually want the IP address to change on the DNS Made Easy name servers in the event of downtime,
make certain the box is checked.
The option for Turn off auto-failover after first failure, disables failover events after the DNS failover action is made for this record.
As soon as any IP is changed by the system, the DNS failover will turn off.
The system monitoring will stay on if presently active, and you will continue to receive emails.
This means that traffic will not be sent back to the primary IP address automatically.
System administrators use this option if they want to manually check the primary server being monitored before traffic is sent back to it.
This option requires that you then revert to the primary IP address manually.
Since we want our IP to automatically revert to the primary IP when available, we will leave this checkbox unchecked.
For IP Address 1, we will enter our primary IP address,
For IP Address 2 we will enter our secondary IP address, Click Ok to submit the changes.
Modifying DNS Failover and System Monitoring records in DNS Made Easy is very simple as well.
Click on any on link under the M / FO column beside your A records,
and the modification window will immediately appear for you to make any necessary changes.
To turn off the monitoring and DNS failover settings, uncheck both the Monitoring and Failover boxes in the modification window.
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