DNS Failover Basics
What is DNS failover?
DNS failover is in fact a two-step process. The first step is to actively monitor the health of your servers. Our monitoring servers check every few minutes based on your monitoring criteria to ensure that your service is running. The second step comes into play when downtime is detected. DNS records are dynamically updated in order to resolve traffic to a backup host. Email notifications are also sent out with the critical information on the failure.
Do I need to host my DNS with you?
If you use failover options that require changing the DNS records for your domain name, you will need to manage your DNS with us. If you simply want to monitor your service and get notified about downtime, you do not have to host your DNS with us.
Do you perform monitoring checks from multiple geographic regions?
Yes. Our monitoring infrastructure is distributed across multiple continents. When a check fails from one region, a verification check is performed from another region before declaring the host down, eliminating false positives caused by regional network issues.
Can I monitor an internal server behind a firewall?
Internal servers can be monitored by either whitelisting our monitoring IP ranges in your firewall, or by exposing the service through a VPN, NAT or reverse proxy that our monitoring servers can reach.
Do you support SSL certificate expiration monitoring?
Yes. SSL monitors validate certificate authenticity and notify you in advance when a certificate is about to expire. The notification lead time is fully configurable, with 30 days being the default.
Pricing
Do you offer a free trial?
Yes. We offer a 14-day free trial for 3 monitors. You do not need to provide any personal information or credit card number to start the trial. At the end of the 14 days, you can switch to a paid service.
How much does the service cost?
The cost of System Monitoring & Failover service is based on the number of monitors that you set up. To start with, 5 monitors costs $9.99/year, 10 for $14.99/year, 20 for $24.99/year, 50 for $49.99/year, 100 for $89.99/year and 500 for $349.99/year.
I ordered Monitoring & Failover service with 5 monitors, can I add more monitors later?
Yes. You can upgrade to 10, 50, 100 and 500 monitors as per your need.
How do I upgrade or downgrade my monitoring plan?
You can upgrade or downgrade your plan at any time directly from the control panel. Upgrades take effect immediately and any prepaid balance is automatically prorated toward the new plan.
Can I cancel my subscription at any time?
We offer a 14-day free trial so that you can fully evaluate the service before purchasing. Refund requests for paid subscriptions are reviewed on a case-by-case basis. Please contact our support team for assistance.
Do you offer refunds?
Yes. You can cancel your monitoring subscription at any time. Your service will continue until the end of the current billing period and will not auto-renew thereafter.
Monitoring
What is a monitor?
A monitor is basically a certain criterion that you set up to ensure that your server is up and running. For example, you can set up a port check monitor on port 25 of your mail server if you want to make sure that SMTP is running normally on your mail server.
What are the monitoring types that you offer?
We currently offer the following monitoring types and are constantly adding more protocols:
- HTTP(s) on a given URL
- Keyword check on a given URL
- Ping on a given host or IP
- Port check on a given host and port
- SSL validity and expiration
- DNS (both TCP and UDP)
What services do you monitor?
Services are monitored on a given host or IP for a variety of protocols including HTTP, HTTPS, DNS, SSL, PING and TCP/IP port. Services monitored include but are not limited to
- HTTP: Web server - port 80
- HTTPS: Secure web server - port 443
- Keyword: Response of HTTP/HTTPS request
- SSL: SSL certificate validity and expiration
- PORT: Monitor any TCP port connectivity
- FTP: File transfer server - port 21
- SMTP: Inbound mail server - port 25
- SSH/SFTP: Secure shell - port 22
- PING: ICMP echo
- DNS: TCP or UDP resolution
How does keyword check work?
A keyword check in a given URL ensures that the right page is displayed, not just any page. This way, you can detect error pages or defaced pages easily and distinguish them from the correct page. Our monitoring server checks for the keyword in the page source returned by the given URL and triggers an alert if the keyword is (not) found. The keyword can be any word on the HTML page or in the page title.
How often do you check my server?
We poll your server as often as the check interval you set up. The check interval can be set anywhere from 1 minute to 24 hours.
How many consecutive failed checks are required before failover is triggered?
By default, failover is triggered after a host fails the configured monitoring criteria for two consecutive checks in order to avoid false positives caused by transient network issues.
How quickly does failover occur after downtime is detected?
Once a monitor confirms that your server is down, the configured failover action is triggered immediately. The actual switchover time experienced by end users depends largely on the TTL of the DNS records involved, which is why we recommend setting your TTL between 60 and 180 seconds.
What IP ranges should I whitelist to allow proper monitoring?
Please whitelist the following IP ranges to ensure proper monitoring.
162.216.242.0/24
72.51.58.0/24
142.202.188.16/29
45.79.53.60
45.79.139.177
45.118.133.11
139.144.225.233
139.162.105.137
139.162.195.230
139.162.241.248
172.105.98.207
172.105.178.214
172.233.26.38
172.234.120.164
172.234.160.126
172.237.28.155
172.237.74.106
172.238.42.108
194.195.117.202
194.195.123.102
2602:ff23:0:8888::/64
2a01:7e00::f03c:91ff:fedd:6af1
2a01:7e00::2000:9eff:fe08:df8f
2400:8901::f03c:93ff:feed:6cc2
2400:8902::f03c:91ff:fee5:9f03
2400:8904::2000:8eff:fe76:5e68
2400:8907::f03c:92ff:fe79:ad70
2400:8907::2000:2aff:feb6:f0f6
2600:3c00::f03c:93ff:fe2b:cc64
2600:3c00::f03c:93ff:fe2b:8509
2600:3c0a::2000:ccff:fe1b:a62f
2600:3c0d::2000:77ff:fee1:7bb6
2600:3c03::2000:e4ff:feaf:b244
2600:3c04::2000:b7ff:fec5:857c
2600:3c07::2000:16ff:fec0:4a88
2600:3c09::2000:39ff:febe:0444
2600:3c15::2000:31ff:fef0:ccc7
2600:3c18::2000:7dff:fed2:103a
I have a web server and a mail server. I want to monitor and failover both. How many monitors do I need?
For this scenario, you will need at least two monitors. One to monitor the SMTP server on port 25, and the other to monitor the web server on port 80. You can also add additional monitors such as keyword check monitor to make sure that the web page is returning the correct content or ping for the server hosts etc.
Getting Notified
Will I get notified if a monitor is down?
Yes, you will get notified. When setting up a monitor, you can set a group of notification contacts who will get alerted when the monitor is down.
What kind of notification methods do you support?
We support a wide range of notification methods so you can be reached on whichever platform works best for you, including:
- Discord
- Email to SMS
- Google Chat
- ilert
- Mattermost
- ntfy
- PagerDuty
- PushBullet
- PushOver
- Rocket.Chat
- Slack
- Teams
- Telegram
- VictorOps
- Webhook
Failover Actions
What failover methods do you support?
You have the following Failover options if your server is detected down:
- Disable the failing A record and enable a backup IP for your domain name
- Disable the failing AAAA record and enable a backup IPv6 for your domain name
- Enable or disable a CNAME record
- Enable or disable an MX record
- Redirect to a custom URL
- Failover to an offline page that displays a custom offline message
Do I need to host my DNS with you?
If you use failover options that require changing the DNS records for your domain name, you will need to manage your DNS with us. If you simply want to monitor your service and get notified about downtime, you do not have to host your DNS with us.
What TTL should I use for my DNS records?
Due to DNS caching, using a TTL between 60 to 180 seconds for your DNS records is suggested to reduce downtime to a minimum. In DNS, TTL specifies how long a resolver is supposed to cache (or remember) the DNS query before the query expires and a new one needs to be done.
Can I configure multiple backup IPs for a single failover monitor?
Yes. You can configure multiple A or AAAA records as backup endpoints. When the primary endpoint is detected down, traffic will be routed to the next available backup IP in your list.
Will my primary server be brought back online automatically once it recovers?
Yes. Once our monitoring servers detect that the primary host is healthy again, the original DNS record is automatically re-enabled and traffic is routed back to it. This behavior is also known as failback and requires no manual intervention.
Troubleshooting
My monitor reports my server as down but it appears to be up. What could be the cause?
The most common causes are firewall rules blocking our monitoring IP ranges, geographic restrictions, rate limiting on the target host or temporary network issues between our monitoring servers and your service. Please ensure that the IP ranges listed in the Monitoring section are whitelisted.
Why am I not receiving email notifications?
Notifications may be filtered as spam or blocked by your mail provider. Please check your spam folder, whitelist our notification sender address and verify that the email address in your notification contact is correct and active.
Why is my failover not triggering even though the monitor shows down?
Verify that the failover action is enabled on the monitor and that the associated DNS record is hosted with us. If the DNS is hosted elsewhere, our failover engine cannot modify the records. Also confirm that the consecutive failure threshold has been met before failover is triggered.
How can I test if failover works correctly?
The easiest way to test failover is to temporarily block traffic from our monitoring IP ranges to your primary host, or to simulate downtime by stopping the monitored service. You should observe the failover action being triggered and the DNS records updated accordingly.
Reporting & Statistics
Do you provide downtime reports?
Yes. Each monitor maintains a complete log of downtime events including the start time, end time, total duration and the reason for the failure as detected by our monitoring servers.
Can I view historical uptime data for my monitors?
Yes. The control panel provides detailed uptime reports, including total uptime percentage, downtime events, response times and average response duration over different time periods.
How long do you retain historical monitoring data?
Detailed monitoring history is retained for up to 12 months for paid accounts. Aggregated uptime statistics are retained for the lifetime of the monitor.
API & Integration
Do you offer an API to manage monitors and failover settings?
Yes. We provide a comprehensive REST API that allows you to create, update, pause, resume and delete monitors, manage notification contacts, retrieve uptime statistics and configure failover actions. Full API documentation is available here.
Can I integrate alerts with third-party tools like Slack or PagerDuty?
Yes. Webhooks can be configured as a notification method to push alerts to Slack, Microsoft Teams, PagerDuty, Discord or any other service that supports incoming webhooks. Email-to-SMS gateways are also supported for SMS-based platforms.
Do you support webhooks for monitoring events?
Yes. Webhooks can be triggered on monitor down events, monitor up events and failover actions. The payload is sent as a JSON POST request to the URL of your choice and includes details such as monitor name, status, timestamp and the reason for the state change.
Can I programmatically pause or resume a monitor?
Yes. Monitors can be paused and resumed at any time through the API or the control panel. This is especially useful when scheduling maintenance windows or temporarily silencing alerts.
Security & Privacy
Are my monitoring credentials encrypted?
Yes. Any credentials provided for authenticated monitoring (such as basic authentication headers or HTTP POST data) are encrypted at rest and transmitted only over secure channels.
Is my monitoring data shared with third parties?
o. Your monitoring data, configuration and uptime statistics are kept strictly private and are never shared or sold to third parties. Please refer to our privacy policy for full details.
Service Reliability & SLA
Do you guarantee any uptime SLA for the monitoring service?
Our monitoring and DNS infrastructure is engineered for 100% uptime through globally distributed, redundant servers. Service level agreements are available for corporate accounts upon request.
How do you handle scheduled maintenance on your monitoring servers?
Maintenance is performed on a rolling basis across our distributed infrastructure so that no single event affects monitoring continuity. Customers are not impacted by routine maintenance.
What happens if your monitoring servers experience an outage?
Our monitoring system is fully redundant. If a node becomes unreachable, monitoring duties are automatically redistributed to healthy nodes in other regions. Customers continue to receive checks and alerts without interruption.