# 🔍 Regex Filter for Even-Numbered Hostnames

This regex is used in **Tanium filters** to match hostnames ending with an **even digit** in their first label.

---

## ✅ Even-Numbered Hostnames (FQDN)

```regex
^[^.]*[02468]\..+
```
^[^.]* → matches the first label (hostname part before the first dot).
[02468] → requires it to end with an even digit.
\..+ → ensures there is a domain suffix (must be a FQDN).

Examples
- pc100.dkcorp.net ✅
- pc8.lab.example.org ✅
- pc101.sud.dkcorp.net ❌ (ends with odd digit 1)
- pc8 ❌ (not a FQDN, no dot)

## ✅ Even-Numbered Hostnames (Optional FQDN)

```regex
^[^.]*[02468](?:\..+)?$
```
^[^.]* → matches the first label (hostname part before the first dot).
[02468] → requires it to end with an even digit.
(?:\..+)? → optional dot + domain (accepts both hostname and FQDN)

✅ Examples
Matches:
- pc8
- pc100
- pc8.lab
- pc100.dkcorp.net

❌ Does not match:
- pc101 (ends with odd digit)
- pc8. (nothing after the dot)
- pc.8 (even digit not at the end of first label)