Last updated: 1/24/01
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Debugging Internet Problems
Even if you are on campus, five computers can be involved in your Internet connection
to the CLL web server (www.cll.wayne.edu). If you are off campus, the number can be ten
computers. If certain of these computers fail or are very busy, your Internet connection
can fail, or you may be unable to establish a connection in the first place. Of course,
two critical computers are the ones at the ends of the connection; your computer, and the
CLL web server. Some of the error messages you may receive are very misleading. But, being
able to debug Internet problems can help you correct them yourself, work around them,
recover from them, or get help.
Never assume that the computer administrators (and I am one of them - the administrator
of www.cll.wayne.edu) are aware of problems and
working to fix them. They have to find out somehow.
How an web page gets to you:
- You use your web browser to request a web page by
- Typing in the URL,
- Clicking on a link, or
- Using a bookmark
The part between the "http://" and the next "/" is the Domain Name
of the web server (computer - for this course, www.cll.wayne.edu) that you are
requesting the web page from. The stuff to the right of the Domain Name tells that web
server which web page (computer file) to send to you. The Domain Name uniquely identifies
a computer connected to the Internet, the web server.
- Your browser contacts a Domain Name Server (DNS) computer to translate the
Domain Name into a numerical IP Address (for the CLL web server, for example,
141.217.142.149). The DNS replies with the IP address.
- Your browser contacts the web server by IP Address to request the page. The request is
forwarded along the way by Gateways (computers, usually not the
"Gateway" brand name) at both ends of the connections, and Routers in
between. If you have recently requested that same page, your browser actually first
requests the date of the page, and if that date has not changed since your last request,
your browser fetches the copy it keeps in its cache.
- The web server replies with the requested information, which travels using the same
system of Gateways and Routers, but perhaps using a different return path.
During a given web session (from the time you open your browser until the time you
close it), the browser remembers the numerical IP Address, so the DNS is not needed again.
This system is "the Internet", and the web is just one application that uses
the Internet. Technically, the Internet is just a "pipeline" for information and
it can carry many forms of information of which the web is just one. Email is another form
of information. Historically, there were many earlier forms which are becoming less used
but still exist. To use the Internet, you need an Internet application at either end of
the connection, that speak complementary languages (or that "use the same protocol").
This is a complex system, and things can go wrong at many different points. That it
works as well as it does is a tribute to the fundamental design, which offers many
alternatives without user intervention, and so is "fault tolerant."
| Problem:
You are using the WSU Internet service to dial on to the Internet with your Access ID and
Password, but your Password, which worked at least once in the past, is not accepted. |
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Possible Solution: The "Authentication
server" is down or the connections to it are down. Call WSU Network Operations Center
at (313) 577-4746 to ask if the authentication server is down, and possibly report the
problem. For problems getting your computer set up to use the WSU Internet service, call
the WSU computer help desk at (313) 577-4778.
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Problem:
when first connecting to the CLL web server, you get an error message similar to the
following:
Depending upon your web browser make and version, this error message may simply say that
this server cannot be located.
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This error message is incorrect; this
server does have a DNS entry and can almost always be found.
Possible solution #1: you have misspelled (not the case if you are using a bookmark that
worked at least once before.Possible solution #2: your Internet connection has failed.
Try connecting again (for example, if you have a modem, disconnecting and redialing.
Possible solution #3: The WSU "DNS server" is down. Call WSU Network
Operations Center at (313) 577-4746 to ask if the DNS server is down, and possibly report
the problem.
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| Problem:
You want to use the web server, but the DNS server is down (see above). |
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Solution #1: Bypass the DNS server and use
the numeric IP address directly by using the URL http://141.217.142.149
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| Problem:
You get an error message that says or includes "The server is not responding" or
something similar. |
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Diagnostic #1: Try connecting to another
WSU web server, for example using http://www.wayne.edu
or http://noc.wayne.edu. If these do not respond (same
error message), then go to Diagnostic #2. Diagnostic #2: Try connecting to a non-WSU web
server, for example using http://www.yahoo.com or http://www.ibm.com.
Possible Solution #1: If only the CLL web server is not responding, get in
touch with me (David Bowen). For a quick fix, the telephone is much better than email, but
if you are not going to call, then email, but that could take a day or two.
Possible Solution #2: If several WSU web servers are down, then there is a good chance
that the whole campus is down. Call WSU Network Operations Center at (313) 577-4746 to ask
if the campus Internet is down, and possibly report the problem.
Possible Solution #3: If you cannot reach anything on the web, check that your Internet
connection is still working. As a last resort, call your Internet Service Provider (if WSU
is your Internet Service Provider, this is the WSU Network Operations Center at (313)
577-4746) and explain your situation, and possibly report a problem.
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| Problem:
You want to use the computer conference, but the CLL web server is down, so you can't get
to the link to the computer conference. Only the CLL web server seems to be down; the
other WSU and non-WSU web servers are responding. |
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The conferencing server is actually a
separate server running on the same computer as the web server, and the conferencing
server has never been known to go down. If you have bookmarked the conference (highly
recommended - bookmark the screen after you have logged in and gotten the number of new
messages), use that bookmark. If not, go directly to the conferencing server using the URL
http://www.cll.wayne.edu:8080/~1/
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| Problem:
You were typing a long message into the conference, and you got an error message saying
that your Internet connection is down, and possibly asking if you want to reconnect. |
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Don't panic! Do not use the back button or
do anything else besides the following: dial in again, then proceed as if nothing
happened. The "information pipeline" connecting your computer and the web server
has sprung a leak or gotten busted. If you don't tell the dumb computers on either end -
your computer and the web server - they won't know, and when you fix the information
pipeline by dialing in again, they will pick up as if nothing happened. However, if this
makes you nervous, perhaps you should learn to compose your messages in Notepad and
copy/paste them into the conference. |
Computers
and Society