This screen shot shows configuration settings for a CAIS dial-up account , other types of accounts will require different settings. Normally you should allow the IP address to be supplied by server . When you connect to CAIS and you have a Static IP address, it should be assigned to you during the authentication process. Close this control panel and save by clicking on the square in the upper left corner. Use version 1.1.1 or newer.
Earlier versions are unstable.
If you are having DNS conflict problems which you cannot resolve, you may need to follow these procedures. Now, restart your Macintosh . DNR will reappear like a bad penny. MacTCP prep will also reappear if MacTCP is being used, else it won't. You can safely trash these two files at any time.