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Setting proxy modes

Setting proxy modes

Load balancers support DNS-only and HTTP proxy modes. You can have HTTP Proxy and DNS-Only domains in the same load balancer region, but the traffic routing behavior differs as follows:

  • Traffic for domains using HTTP Proxy mode is routed based on the data center associated with the user making the request.
  • Traffic for domains using DNS-Only mode is routed based on the data center associated with the user’s recursive resolver (DNS recursor).

HTTP Proxy mode

In HTTP Proxy mode, load balancers have an automatic TTL. CIS announces IBM IP addresses externally, but protects (masks) your origin server IP addresses. When proxied through CIS, origin IP addresses should be public. Any changes to your load balancer propagate within seconds inside CIS, including any failover events.

Setting the load balancer to HTTP Proxy mode offers the following benefits:

  • Failover is faster, because external DNS caches that don't respect short DNS TTLs do not impact failover performance.
  • The "automatic" TTL (five minutes) reduces the number of authoritative queries made against CIS without impacting failover performance.

DNS-Only mode

In DNS-Only mode, you can configure load balancers to set a TTL from 30 seconds to 10 minutes. CIS serves the addresses of the healthy origin servers directly, but relies on DNS resolvers respecting the short TTL to re-query the CIS DNS for an updated list of healthy addresses.