Scalability, high availability and performance are critical to service provider deployments. While many service providers deploy there infrastructure at a single location or multiple location, these deployments are subject to a number of inherent limitations, such as:
- If the site loses connectivity to all or part of the public Internet, it will be inaccessible to users and customers, which can have significant impact on the business.
- Users accessing the site from geographically distant locations may experience large and highly variable delays, which are exacerbated by the large number of round trips that HTTP requires to transfer content.
NetScaler appliance’s Global Server Load Balancing (GSLB) overcomes these problems by distributing traffic among sites deployed in multiple geographic locations. By serving content from many different points in the Internet, GSLB alleviates the impact of network bandwidth bottlenecks and provides robustness in case of network failures at a particular site. Users can be automatically directed to the nearest or least loaded site at the time of the request, minimizing the likelihood of long download delays and/or service disruptions.
You can use NetScaler appliance’s global server load balancing for:
- Disaster recovery or high availability by configuring an Active-standby data center setup that consists of an active and a standby data center. When a failover occurs as a result of a disaster event, the standby data center becomes operational.
- High availability and speed by configuring an active-active data center setup that consists of multiple active data centers. Client requests are load balanced across active data centers.
- Directing client requests to the data center that is closest in geographical distance or network distance by configuring a proximity setup.
- Full-DNS resolutions, GSLB processes DNS queries of the A, AAAA and CNAME types, and the DNS function option can process DNS queries of all other types, such as MX and PTR. Also, if the recursive resolution is enabled, the NetScaler will forward DNS queries for domain names that are not configured on the NetScaler appliance.