GSLB Farms Overview

SKUDONET can also be used like your Authoritative DNS server which offers load-balancing capabilities and backend health checks. The Global Service Load Balancing module (GSLB) allows load balancing at a DNS level. At this level, client requests are decided by a load balancer that uses smart algorithms to redirect traffic to active-active or active-passive accessibility of data centers.

In this section, you’ll learn how to manage GSLB farms using the SKUDONET appliance. This farm profile controls all load balancing services and applications at the DNS level. We’ll help you manage these farms and redirect client requests to the services of their most convenience.

The scheme below shows the use case for load balancing across various data centers using GSLB infrastructure and an HTTPS webpage (eg. google.com), in this hypothetic example google.com is a domain name managed by the SKUDONET Authoritative DNS system or GSLB module.

1. The client requires an HTTPS connection against the host www.google.com.
2. The DNS client configuration finds the nameservers for the domain google.com
3. The Nameservers for domain google.com is 162.243.5.109. This IP is a virtual IP configured in the SKUDOET Load balancer with a GSLB farm.
4. The client requests the IP for the host www.google.com to the name server 162.243.5.109
5. The nameserver replies with two IPs: 24.107.255.201 and 80.245.63.251 but the second is not reachable through port 443.
6. The client connects against the available IP for www.google.com which is 24.107.255.201.

The GSLB farm configured in the SKUDONET GSLB module includes a service called poolweb, this service is configured in active-active with the two available IPs 24.107.255.201, 80.245.63.251. The GSLB module is checking the backend status using port 443. When one backend doesn’t reply to this check, the load balancer marks the backend in DOWN mode, and this IP is not replied to the clients.

GSLB services also can be configured in active-passive. In case the active node fails then the other node’s IP will be replied by DNS resolution for the host. This configuration is used for Data center disaster recovery, creating a full Active – Passive data center load balancing.

GSLB Farms Lists

These are the farm properties each farm holds, and their adjacent fields are described below.

Name. A unique descriptive name of the farm.
Virtual IP. The IP address that is receiving the incoming traffic.
Virtual Port. The port that is managing the traffic. By default 53 UDP and TCP.
Status. The status shows indicators of farm availability.

• Green. Means UP. The farm is running and all servers are UP.
• Red. Means DOWN. The farm has stopped running.
• Yellow. Means RESTART NEEDED. There are recent changes that need a farm restart to be applied.
•  Black. Means CRITICAL. The farm is UP but there is no server response, or all servers are in maintenance mode.
• Blue. Means PROBLEM. The farm is running but at least one server is down.

GSLB Farm Actions

Below is the description of farm actions.

Edit. Apply any change to the farm, like global parameters, Services or Zones. Note that the farm Name only changes when the farm is down.
Restart. Reboots an active farm to apply a new configuration.
Stop. Switches off an active farm. When the farm is stopped the port and IP binding on the Operating System are released.
Start. Starts the farm if it is down.
Delete. Deletes all configuration files. The IP(s) and PORT(s) will be released for being used by another farm.