DNS round-robin load-balancing

You can make GSLB return several IP addresses from healthy datacenters in a round-robin weighted fashion.

1. In the Services tab, click gslb setup.

   

2. Add a listen directive for each IP address/network port pair at which the GSLB should listen for DNS queries. By default, it listens on all IP addresses (0.0.0.0) at port 53.

3. To enable the service to start automatically when the appliance boots, delete the no autostart line, click OK and then Close.

4. In the Services tab, click [advanced mode], then edit the gslb configuration.

   

   The current configuration displays.

   zone example.com
     ttl 10
     # ORIGIN records
     record @ SOA ns1.example.com hostmaster.example.com 1 86400 3600 3600 3600 60
     record @ NS  ns1.example.com
     record @ ttl 3600 MX 100 mail1.example.com
   
     # Static records
     record ns1   ttl 20 A 10.0.0.1
     record mail1 ttl 20 A 10.0.0.2

5. Add a new list record to the zone section.

   The record section directives syntax is as follows.

   Record type	Description
   list	Dynamic record followed by list of space-separated answer-list names.

   The list record www contains one answer-list: dc1.

   zone example.com
     ttl 10
     # ORIGIN records
     record @ SOA ns1.example.com hostmaster.example.com 1 86400 3600 3600 3600 60
     record @ NS  ns1.example.com
     record @ ttl 3600 MX 100 mail1.example.com
   
     # Static records
     record ns1   ttl 20 A 10.0.0.1
     record mail1 ttl 20 A 10.0.0.2
   
     # Dynamic records
     record www ttl 20 list dc1

6. Create answer-list sections that match the names you listed in the zone section.

   zone example.com
     ttl 10
     # ORIGIN records
     record @ SOA ns1.example.com hostmaster.example.com 1 86400 3600 3600 3600 60
     record @ NS  ns1.example.com
     record @ ttl 3600 MX 100 mail1.example.com
   
     # Static records
     record ns1   ttl 20 A 10.0.0.1
     record mail1 ttl 20 A 10.0.0.2
   
     # Dynamic records
     record www ttl 20 list dc1
   
   answer-list dc1
     method single-rr
     option httpchk
     http-check connect
     http-check send uri /health.html hdr host www.example.com
     answer-record srv1 20.0.0.1 weight 10
     answer-record srv2 20.0.0.2 weight 20

   The answer-list section directives syntax is as follows.

   Directive	Description
   method	Set the single-rr parameter.
   option	Specify httpchk to monitor the health of servers.
   http-check	Set any relevant health check parameters.
   answer-record	Enter any number of answer-record directives along with the corresponding IP addresses. Weights determine how often a particular IP address will be returned, with higher weights being chosen more often. By specifying method single-rr, HAProxy ALOHA alternates which IP for a datacenter it sends to clients in order to distribute traffic across all servers. In that case, the odds of a server's IP being returned is server weight / sum of all server weights.

7. Save your configuration, close the configuration editor, then apply your changes on the gslb line in the Services tab.

   

8. In the Setup tab, click Save under Local Configuration to persist your changes after a reboot.

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