8 August 2026

Why a DNS Name Can Be Better Than an IP for Egress Policy

Cloud and SaaS services move between addresses. Policy often expresses intent more accurately when it follows the application hostname.

Suppose the requirement is:

Traffic to a particular SaaS application must leave through a controlled egress address.

An IP-based rule can work, but cloud services and CDNs make the mapping increasingly fragile.

The business requirement is normally about:

application.example

not:

whatever IP ranges happen to host it today

That leads to a useful principle:

Where the platform supports it, express application policy using application identity rather than oversized infrastructure ranges.

Domain-aware policy can reduce:

• large provider subnet lists
• unrelated traffic being captured
• constant IP-range maintenance
• policies that are difficult to understand later

There are still important details to validate, particularly DNS behaviour, direct-IP connections and applications that cache addresses.

But as a policy primitive, a hostname can often represent the original intent much better than a changing collection of IP ranges.

For the longer version of this topic, see the full article on domain-aware egress steering.