Ok, here is my situation.
Internal domain: company.local
External websites hosted on the same provider: company.com and company1.com
The symptoms are that every so often, internal clients cannot access external sites. Mails are hosted on external provider therefore when that happens, emails are not available either. External host is reachable from outside the company's network
Ping return correct IP from inside and outside the network.
If I do tracert from outside the network, the trace is completed normally in 22 hops.
If I do tracert from inside the network, the trace stops after the 21st hop, and cannot find the 22nd and final hop. I get a series of "Request timed out" instead. I feel this is a good hint, but I am unable to explain it.
Does anyone have a clue?