testing for Internet connection

[Chipp Walters]

Alex,

You are correct in that if Dns is down then my function will return 
false, exactly how I wish it to work.

All my apps connect to domains, not IPaddresses, so a positive 
connecting to an IPaddress wouldn't explain to my users why they cannot 
connect to a domain.

Perhaps a combination ping then get url may suffice. I've over 10 apps 
testing with google, with no problems so far. I imagine google can 
withstand a dos better than my servers.

On Sun, 19 Dec 2004 6:15 am, Alex Tweedly wrote:
which can be avoided by using numeric IP addresses rather than host 
names.  Using a host name will cause the Rev app to block for 10-30 
seconds while it waits for a DNS response (see BZ 2117 for details -  
Mark W.'s solution is a non-blocking ping)
>
> This problem happens to me all the time, because I use my laptop 
> connected to an ethernet which connects to the internet through another 
> computer using a dial-up line, and the dial-up is often disconnected. 
> Laptop thinks it has a connection (the ethernet is up) and thinks it 
> has DNS servers it can reach (because the main computer acts as a DNS 
> proxy) - but when it queries a host name, it is blocked until the DNS 
> response times out.
>
>> if your user is not connected, they will probably get an 'invalid host'
>> answer. Testing against google seems always to work for me. I figure, 
>> if
>> they can't get to google, then they can't get to my server.
>
> Google has been the target of a number of DoS attacks, so there have 
> been at least two occasions when large parts of the net couldn't get an 
> answer from Google, but could have done from you.
>
> -- Alex.