Managing Multiple Internet Connections

Life would be so simple if computers and people just stayed put, but that's not the way the world works anymore. Portable computers now account for more than half of the computers sold in the United States. Managing Internet connections from multiple locations can be a little tricky.

I'll talk a bit more about the ins and outs of traveling with your computer in Chapter 18, where the topic is remote networking.

The issue comes up with plain Internet connectivity as well, so let me share some tips:

• If you use a LAN Internet connection in the office and a modem connection elsewhere, bring up the Connections tab of the Internet Properties dialog box, and choose Dial Whenever a Network Connection Is Not Present, as I discussed in the previous section, "Changing the Default Connection."

• If you use different LAN connections in different locations, see "Multiple LAN Connections" in Chapter 18.

• If you use a dial-up Internet service provider with different local access numbers in different locations, life is a bit more difficult. It would be great if Windows would let you associate a distinct dial-up number with each dialing location, but it doesn'tdialing locations just adjust the area code and dialing prefixes.

  The solution is to make separate connection icons for each location's access number. After you set up and test one connection, right-click its icon and select Create Copy. Rename the icon using the alternate city in the name; for example, I might name my icons "My ISP Berkeley," "My ISP Freestone," and so on. Finally, open the Properties page for the new icon, and set the appropriate local access number and dialing location.

  In this case, it's best to tell Windows never to automatically dial a connection (as shown earlier in "Changing the Default Connection") because it will not know which of several connections is the right one to use; it might dial a long-distance number without you noticing.

Moving around from one network to another or one ISP to another can also cause major headaches when you try to send email. The reason is that outgoing email has to be sent from your email program to a mail server called an SMTP server. These servers are set up to reject incoming email from any unidentified user who is not directly connected to or dialed-up to their own network. For example, if you have Outlook Express set up to send email through your company's mail server and you try to send mail from home, your company's server will see that you're connected from a foreign networkthat is, your ISP's networkand may reject the message, calling it an "attempt to relay mail."

Likewise, you may experience the same problem if you are set up to send through your ISP's mail server and then try to send mail from a wireless connection at an Internet café.

For some tips on handling this problem, p. 388.