Subdomain naming patterns

What FTSE 100 subdomain names reveal, aggregated from 17463 hostnames observed via Certificate Transparency and direct crawl. A hostname here means a certificate was issued for that name (or it was linked from a crawled page) — not that it resolves or serves traffic today. Each square is one company; hover it for the name.

Lifecycle environment

5436 of 17463 subdomain names carry a recognisable environment tag (prod, staging, dev, test, sandbox, or a CI preview build).

Tag	Subdomains	Example
Staging / UAT	1516	`ava-uat.mandg.com`
Test / QA	1322	`ava-sit.mandg.com`
Dev	1563	`us.dev.azbrain.astrazeneca.com`
Production	608	`prod-aiassist.astrazeneca.com`
Sandbox / demo	153	`api-sandbox.autotrader.co.uk`
CI preview	274	`dev-preview.aberdeeninvestments.com`

Functional / technology signal

2641 of 17463 subdomain names name a specific tool, platform, or function directly.

Signal	Subdomains	Example
API	1164	`api.dev01.azbrain.astrazeneca.com`
Remote access / auth	462	`fat-login.mandg.com`
Admin	193	`prod-admin-aiassist.astrazeneca.com`
Dev / infra tooling	215	`jira-test.astrazeneca.com`
Cloud / platform	559	`som-ct.test1.fd2c3ab816ae5c4.euwe2.prd-plat.aws.bt.com`
Mail	48	`view.mail.barclays.com`

Classification is pattern-matching on the hostname text itself (see how patterns are matched) — a name containing "test" is tagged Test/QA whether or not it is actually a test system today.