Server Set Properties dialog - Update DNS tab
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Server Set Properties dialog - Update DNS tab
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Figure 1: The Update DNS tab on Server Set Properties. Update DNS (off=monitoring only) Use to enable / disable DNS update for this Server Set. The main purpose of Simple Failover is to provide failover protection by monitoring your servers and updating DNS accordingly. However, you can also using Simple Failover just for simple server monitoring by leaving this option off. Use default DNS servers (Options dialog) Instead of entering specific DNS servers for this server set, you can select this option to use the default DNS servers specified in the Options dialog. Use the following DNS servers: Specify the DNS Servers that you want Simple Failover to update for this Server Set. When you add or edit a DNS server, you can specify the DNS update method and associated properties in the DNS Server Properties dialog. Also update DNS for these domain names (aliases) Sometimes a single Internet service can be accessed via several different domain names. The service provides the exact same contents / functionality no matter which domain name is used. A typical example of this is a web-site which can be accessed both with and without the www domain name prefix (which are technically two different domain names). There is usually no reason for testing such a service with more than one of the domain names, yet in case of a failure, you still want to update DNS for all the domain names so that they all point to the functional server IP address. This option lets you specify additional domain names to be updated for a server set. Please note: we do not recommend using DNS CNAME-records for alias domain names because DNS responses containing such records are cached differently by Internet Explorer (typically for a fixed period of 30 minutes). Please note: depending on your license type the number of DNS Alias domain name may be limited. Options for DNS servers using the DNS, DNSTSIG or MSWMI update methods only: Create DNS records for You can choose to either create DNS records for The first responding server only or All responding servers (round robin). Use the first option if you always want traffic to be directed to the first server (on the Servers tab) unless there is a problem with this server. Use the second option if you want traffic to be rotated between all the available servers (make sure to also enable the round robin option on the DNS servers). DNS A-record TTL Defines the TTL (Time To Live) of the DNS records created by Simple Failover. Generally this should be set very low to avoid caching on other DNS servers. However setting it too low may cause excessive DNS traffic. We recommend a value of half the Server Set polling interval or less. The default setting is 30 seconds. |
