Missing IPs in my log files

Cart shows customer IP, Logs sometimes don't

[uk_dokey]

We use an independant secure server that accurately logs all customers IP adresses. I regularly then check our web logs to track down these IP addresses and find out where they came from/referrer. I find that I can only see about 50% of these IP addresses in my logs and I am getting concerned. Could it be that the LOG files aren't correct? Is this possible?
I use a lot of cpc (cost per click) schemes so its vitally important for me to know where I'm getting business from so I can work out my ROI (return on investment)

[Lisa]

yeah, sounds like a problem with your logging. Every request will come from an IP address. Very odd.

[minnapple]

I have experienced the same thing.

Hate it when I search the log for the buyers ip and get a "not found".

Not sure if there is some ip cloaking going on.
At first I was worried about fraudulent
purchases, but all went through ok.

When I get time, I am going to go back and try to track a few of these "not found" futher by purchase date:time.

[bird]

Does the server have reverse DNS resolving activated? In that case, those IPs that do resolve to a host name will be listed by name, and not by IP. You can do a nslookup on the IP and then search your logs for that name.

[uk_dokey]

I have checked by time also but the customer just didn't exist according to my logs. Surely can't be cloaking I miss out on about 50% of IPs in the log, surfers can't be that clued up. Ahh well I will have tofind a way around it. Just another question do you find that google traffic is non productive. I get plebty of hits from them but little sales. Ask seems to be the best for sales. Just wanderd if it was the same for you all?

[keyplyr]

Your server logs only show an IP address that was served files from your domain. If your visitor drew your pages/files from a cache, he/she would not be in that log. Internet providers, proxy servers, LANs, even browsers use cache to more efficiently handle down stream bandwidth.