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Last Updated: Jan 25, 2021

Basic concepts

TermDescription
Global Traffic ManagerGlobal Traffic Manager (GTM) is a DNS-based service that allows you to balance concurrent traffic across multiple nodes and access the nearest node where your application is deployed. Based on health checks, Global Traffic Manager isolates faulty applications or switches these applications to healthy nodes for disaster recovery.
CNAME access domain nameAfter you purchase GTM, the system automatically allocates a domain name record for each instance that is generated. You can connect the required domain names to a GTM instance through CNAME.

Access policy based on geographical locations

A geographical location-based access policy uses the intelligent DNS resolution feature to specify the required address pools for visitors from different networks or regions. This type of access policy allows global users to access the nearest node based on the location and accelerate content delivery.

Access policy based on latency

A latency-based access policy detects the latency between the location of a user and the region in which the application is deployed. This type of access policy routes user requests to an application server cluster that has the lowest latency.

Primary address pool set

The primary address pool set consists of a group of address pools of the same type based on different business scenarios. By default, inbound traffic is distributed to the primary address pool set.

Secondary address pool setWhen application services fail, GTM switches inbound traffic from the primary address pool set to the secondary address pool set. This configuration allows you to reduce the out-of-service time.
Address poolAn address pool consists of a set of IP addresses that provide the same service. Compared with a single IP address, this configuration allows you to balance workloads across multiple IP addresses. To facilitate management, GTM uses address pools to manage IP addresses. You can add IP addresses or domain names to an address pool.

Return all addresses

GTM resolves the domain names of application services into multiple IP addresses. Access traffic is evenly distributed to each IP address.
Return addresses by weightGTM resolves the domain names of application services into multiple IP addresses. Each IP address accepts a percentage of access traffic based on the specified weight.
Health checkThis feature uses a group of monitoring nodes to detect the availability of application services that are running on IP addresses by using ping, TCP, or HTTP tools. This feature also checks whether these application services function as expected based on the specified alert rule.
Traffic schedulingThis feature allows you to balance multiple user requests across different destination servers based on the analytical results of real-time network traffic.

Maximum number of returned addresses

If you use a latency-based access policy and an application service has multiple IP addresses, the system returns one or more resolution results that have the lowest latency. Valid values: 1 to 8.

Latency resolution scheduling optimization

If the maximum number of returned addresses is greater than 1, you can enable the latency resolution scheduling optimization feature. This feature allows the system to check all the addresses and return the optimal addresses. The number is less than or equal to the maximum number of returned addresses.

SNI

Server Name Indication (SNI) is a technology that is defined in RFC 4366. SNI is used to improve Secure Sockets Layer (SSL) and Transport Layer Security (TLS). In SSLv3 and TSLv1, this technology is enabled. SNI allows clients to submit hostnames as a part of ClientHello messages during the SSL handshake process. This allows servers to select the related regions and return the required certificates.