Create dns.md

Author: TimoDJatomika

dns.md

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+# DNS
+The Edge Router can function as a little DNS Server. But keep in mind that this is only a basic DNS Server. You can only configure A Records. 
+
+## enable DNS
+Which Interface should be allowed to query the DNS Server ?
+
+```bash
+set service dns forwarding listen-on eth2.10
+set service dns forwarding listen-on eth2.20
+set service dns forwarding listen-on eth2.30
+set service dns forwarding listen-on eth2
+```
+
+## add an entry
+You just need the IP Address and the hostname. You have to give the "static-host-mapping" a name. In this case it's `cgn-qemu-01` but this has nothing to do with the DNS name. 
+Just make sure that this is unique. 
+
+```bash
+set system static-host-mapping host-name cgn-qemu-01 alias cgn-qemu-01.example.com
+set system static-host-mapping host-name cgn-qemu-01 inet 10.10.99.130
+```
+
+You can also have more then one Hostname pointing to one IP Address 
+
+```bash
+set system static-host-mapping host-name cgn-vm-win10 alias cgn-vm-win10.example.com
+set system static-host-mapping host-name cgn-vm-win10 alias cgn-win-mgmt.example.com
+set system static-host-mapping host-name cgn-vm-win10 alias prtg.example.com
+set system static-host-mapping host-name cgn-vm-win10 inet 10.10.99.111
+
+```