[Solved] Cronjob / Script not working for update of A-record

[cantor]

I want to automatically update the A-record of one of my subdomains with the WAN-IP of my pfSense (2.0.1).
For this reason pfSense should call once a day (triggered by a cron job) an URL like the following:
https://sub.domain.tld/dns.php?<lots of="" parameters="">?ip=<wan-ip></wan-ip>?<more parameters="">.

So far I just did simple configuration via GUI, so unfortunately I don't know how I can generate the above link with the actual WAN-IP included, and call it by a cron job.

I'd really be happy for any hints and help.

Thanks a lot in advance.
Juergen

//edit:
Problem solved! :-)</more></lots>