Inside Out

Choose your test site carefully

In some cases, pinging an external website results in a string of "Request timed out" messages, even when you have no trouble reaching those sites . Don't be misled . Some popular sites, including Microsoft's home page, www.microsoft.com, block all ICMP traffic, including Ping packets, as a routine security measure. Try pinging several sites before concluding that your internet connection is broken.

If either of the two final steps in this process fails, your problem might be caused by DNS problems, as described later in this chapter. (For details, see "Resolving DNS Issues" on page 683.) To eliminate this possibility, ping the numeric IP address of a computer outside your network instead. (Of course, if you're having DNS problems, you might have a hard time finding an IP address to ping!) If you can ping a website using its IP address but not by using its name, DNS problems are indicated.

If you suspect that there's a problem on the internet between your computer and a distant host or server, use the Traceroute utility (Tracert. exe) to pinpoint the problem . Like the Ping command, this utility works from a command line . You specify the target (a host name or IP address) using the syntax tracert target_name, and the utility sends a series of packets out, measuring the time it takes to reach each "hop" along the route . Timeouts or unusually slow performance indicate a connectivity problem . If the response time from your network to the first hop is much higher than the other hops, you might have a problem with the connection to your internet service provider (ISP); in that case, a call to your ISP's support line is in order. Problems farther along in the traceroute might indicate congestion or hardware problems in distant parts of the internet that are out of your ISP's hands and that might disappear when you check another URI that follows a different path through the internet

If your testing produces inconsistent results, rule out the possibility that a firewall program or Network Address Translation (NAT) device (such as a router or residential gateway) is

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to blame. If you're using a third-party firewall program, disable it temporarily. Try bypassing your router and connecting directly to a broadband connection such as a DSL or cable modem . (Use this configuration only for testing and only very briefly because it exposes your computer to various attacks.)

If the Ping test works with the firewall or NAT device out of the picture, you can rule out network problems and conclude that the firewall software or router is misconfigured. After you complete your testing, be sure to enable the firewall and router again!

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