Sometimes you will need to connect to a router that either has a dynamic IP or a domain name instead of directly to the IP address. This is easily achieved using RouterOS with a simple script. Using the script below you will need to change PPP-INTERFACE to the name of your PPP interface and VPN.YOURDOMAIN.COM to the domain name of what you are trying to connect to.
/system script add name="CBrown-VPN DNS" policy=\ ftp,reboot,read,write,policy,test,winbox,password source=":global pptpinte\ rfacename \"PPP-INTERFACE\"\r\ \n:global pptpdnsname \"VPN.YOURDOMAIN.COM\"\r\ \n:global pptpdnsip [:resolve \$pptpdnsname]\r\ \n:global currentip [/interface pptp-client get \$pptpinterfacename connec\ t-to]\r\ \n:if (\$currentip != \$pptpdnsip) do={ /interface pptp-client set [find n\ ame=\$pptpinterfacename] connect-to=\$pptpdnsip}\r\ \n}"