Web mail windows will also generate periodic AJAX HTTP requests to check for mail updates. I haven't investigated but I would wager that it would also be downloading updated ads from
o.aolcdn.com during that time. I haven't been on Aol in forever but if you have chat windows or anything else that periodically updates it might be sending requests that you aren't aware of.
If you are using a browser (e.g., Chrome) that prefetches content then even more can be generated. Also, if you've disabled caching of Web content to prevent being tracked at work, that could be a source of an increased number of requests as your browser needs to refetch data that you saw during your last browsring session.
It's also entirely possible you have a virus or other malware making those requests as well.