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glb-proxy-modes.md

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copyright lastupdated keywords subcollection
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2020, 2024
2024-07-17
cis

{{site.data.keyword.attribute-definition-list}}

Setting proxy modes

{: #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

{: #http-proxy-mode}

In HTTP Proxy mode, load balancers have an automatic TTL. {{site.data.keyword.cis_short_notm}} announces IBM IP addresses externally, but protects (masks) your origin server IP addresses. When proxied through {{site.data.keyword.cis_short_notm}}, origin IP addresses should be public. Any changes to your load balancer propagate within seconds inside {{site.data.keyword.cis_short_notm}}, 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 {{site.data.keyword.cis_short_notm}} without impacting failover performance.

DNS-Only mode

{: #dns-only-mode}

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