Web Performance Tuning, 2nd Edition

Chapter 1. The Quick and the Dead

While this book contains a lot of detailed information about monitoring, load testing, problem analysis, and background about how things work, I often find myself referring to this small set of questions and answers I wrote up to quickly diagnose and treat the most common problems. Since a majority of problems can be solved by simply reading through this list and checking things off, I provide it here right up front. There are many references to concepts that have not been discussed yet, but they are explained later in the book.

Questions for the Browser Side

First, here are the things you might try if your browser seems slow or unresponsive:

Is Your Modem On?

If you have an external modem, the power light should be lit to indicate that the modem is on.

Is Your Modem Connected to Your Computer?

If you have an external modem, make sure the modem cable is connected to your computer. Then try manually sending something to the modem. From a Linux shell you can do this:

% echo AT > /dev/modem

From a DOS prompt on a Windows machine you can do this:

% echo AT > COM1

If your modem is connected, you will see the send and read lights flash as the modem responds OK to the AT command. If the lights do not flash, either the modem is not connected, or you have configured it for the wrong COM port, PCMCIA slot, or other attachment point.

Did the Other End Hang Up on You?

External modems should have a light labeled CD (Carrier Detect) to indicate whether ...