How+to...localize+an+Internet+Access+Problem

How to... Localize an Internet Access Problem
How to Localize an Internet Access Problem

From time to time we all get a message from our browser to the effect that “the server cannot be accessed”, or, when trying to download e-mail, we don't get any mail and the request times out. There is no hint as to where the problem is – whether the computer has somehow failed or whether the problem lines in one of the dozens of links between the computer and the information source. It is possible to localize the problem using the procedure outlined below. The location of the problem determines whether there is an action that one personally can/should/must take to fix it, or whether it is beyond one's personal control and the fix can be effected only by someone in the outside world. Sorry, you will have to use the command line and actually type a few characters.

Warning: These instructions were worked out using Windows XP. I checked them against a single copy of Win7, which varied, as noted below, slightly, from XP.

First of all, get to a “command prompt” by clicking “Start”, “run”, typing “ cmd “ (without the quotes) in the box, and hitting , (or clicking OK). You should get a DOS-like non-GUI screen

Find essential information about your computer and its connection by typing “ ipconfig /all “ (again, and ALWAYS, no quotes)

Note what ipconfig displays, and save the following results: IP Address (e.g., my computer currently is 192.168.4.196) Note: Win7 calls this “ IPv4 Address “ Default Gateway (expect it to be 192.168.4.1) DNS Servers (expect 68.105.29.12 and 68.105.28.12)

With these preliminaries out of the way,

A Still from the command prompt, type “ ping 127.0.0.1  “ You should get a reply. If you don't get one, the computer itself is very sick. You should always get a reply.

B. Ping your own IP address. For me, type “ ping 192.168.4.196 “ If your internal network interface is working, you should get a reply. If you don't get a reply, your problem is internal. [Conceivably, the NIC may be OK but disabled. It is possible to disable the NIC {Start >> Control Panel >> Network Connections). If the card (or equivalent) disabled, the ping will fail.]

C. ping the router which connects you to the outside world, by “ ping 192.168.x.y “, where “x” can be either a 1 or a zero, and y can be either a 1 or a zero. Thus, there are four possibilities. One of them should work. For me, in a Garden Home, pinging a Cisco router in a box on my outside wall, what works is 192.168.0.1. The other three possibilities do not work. Same story, exactly, for the computers in LV136. It is obviously a good idea to find out which address is right for you at a time when the system is working correctly. Invariably, I have been able to fix a failure to ping this point by by resetting my router. Yet, most recently, such a fix did not work and Charley fixed it by replacing faulty equipment in La Vista. (?)

D ping the Default Gateway: “ ping 192.168.4.1 “ (probably) This is a piece of hardware belonging to LaPosada, which sometimes goes down. If this ping fails (and the former sites are OK), the problem is La Posada's. You are blocked from the world outside the Campus, and something needs resetting. Call 0 (service center) for help.

E: ping Cox's DNS server “ ping 68.105.29.12 “ (probably) If you get a reply, you are getting through to Cox, and their DNS server is working. Sometimes Cox's DNS server goes down but the internet is still possible. In this case, if you should be able to ping 4.2.2.2 (a generic nationwide DNS server). Thus, with a browser, you could not access Google with “ http://google.com g (which requires a working DNS), but could with http://74.125.65.105, which is one of Google's IP addresses. If Cox's DNS doesn't work try g ping 4.2.2.2 gwhich is a non-Cox generic DNS server. If you can't get a reply from one of these DNS servers (and the earlier pings have been successful), the problem lies outside of LaPosada, and you will have to wait for Cox and/or someone even more remote to get its act together.

H M Bath tel x4261 2010 July 11.

SUMMARY Internal to your computer: 127.0.0.1 IP Address (Ipv4 Address) of your computer (ex: 192.168.4.123) Your very local network 192.168.0.1 (the router, or routers) LaPosada's network server 192.168.4.1 Cox's DNS server 68.125.29.12 (example only!) Nationwide DNS Server 4.2.2.2

