Traffic Steering Optimizations for Salesforce Edge Network Users

Background

DNS Primer

IP addresses are what two hosts use to talk to each other. IP addresses are difficult to remember and cumbersome to change following topology updates. This scenario is where the Domain Name System (DNS) steps in. A server or collection of servers takes requests for names and returns the IP address. Known as resolvers, these servers can be authoritative or non-authoritative. Non-authoritative resolvers respond to DNS requests by finding and asking authoritative resolvers and they usually cache the result. Authoritative resolvers respond to DNS requests independently. They don’t need to consult with any other resolvers.

Geographic Load Balancing

Using indirect mapping between the DNS name and IP address, a geographic load balancer can be constructed. The geographic load balancer, also known as a global server load balancer, is an authoritative DNS resolver that returns different IP addresses based on information received from the DNS request. This information can be the client's IP address, TCP connection parameters, the time of day, the physical port that the request was received on, or information in extended fields of the DNS request payload.

Proxies

It’s often advantageous for corporate IT admins to install proxy servers on their networks. These servers provide a single point of audit and policy enforcement. Clients who want to obtain a resource on the internet send the request to the proxy server. The proxy server fetches the resource on behalf of the client. The HTTP method CONNECT is used in HTTPS to create a secure connection between the client and server.

Topology of the Customer’s DNS

The customer’s network relies on a few DNS resolvers which can be their own or provided by their internet service provider. Consult with your internet service provider or network operator to determine the IP addresses of your DNS resolvers and their physical location. Use any available GeoIP database to verify the physical location and the GeoIP location match. Clients from most offices around the world connect to these DNS resolvers to make DNS requests. The following sections assume that you know where your resolver is physically located.

Problem Statement

Salesforce Edge uses geographic load balancing and multiple globally distributed points of presence to cache objects and terminate TLS closer to the end user. Clients are routed to the closest data center by using DNS. Salesforce's DNS servers rely on the location of the customer’s DNS resolvers.