> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/cortex-xsiam-developer-guide/cortex-xsiam-development-guide/indicators/domain-extraction.md).

# Domain extraction

The Cortex XSIAM domain indicator type is built using regular expression and a formatting script. The following describes the domain extraction components and what output you should expect when extracting indicators of type domain.

#### Domain extraction components

There are two components when extracting domain indicators:

* Regular expression
* Formatting script

#### Regular expression

When text is given, a domain regular expression will try to catch a valid domain based on the following characteristics:

* A domain with ASCII and non-ASCII characters
* Escaped and unescaped domains

The regular expression can extract domains from one of the following:

* Explicit domain
* URL
* Email address

#### Formatting script

After extracting the domain using a regular expression, an `ExtractDomainAndFQDNFromUrlAndEmail` formatting script iterates on each given domain and does the following:

1. Replaces "\[.]" with ".".

   For example:

   `www[.]example.com --> www.example.com`
2. Validate the Top-Level-Domain to avoid file extension false positives.

   Excludes ‘.zip’ Top-Level-Domain by default.
3. Returns the formatted domain.

#### Common domain structures

* `example.com`
* `www.example.com`
* `xn--t1e2s3t4.com`
* `www.xn--t1e2s3t4.com`
* `www.example.co.uk`
* `example.co.uk`
* `subtest.example.com`
* `www.example.example.com`
* `öexample.com`
* `exampleö.com`
* `www.exampleö.com`
* `www.examöle.com`

For more information, see [Indicator extraction](/cortex-xsiam-developer-guide/cortex-xsiam-development-guide/indicators.md).


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