Users can only access external websites. Which of the following is the MOST likely cause of this problem?

An incorrect gateway address would prevent access to any resources outside the local subnet, including external websites.

An improper subnet mask would affect network communication broadly, potentially preventing access to resources both internal and external depending on the error.

Clearing the DNS cache on a workstation would temporarily remove cached entries but not prevent new resolutions from occurring if the DNS server itself is functioning correctly.

If the internal DNS zone is deleted, the DNS server will no longer have records to resolve internal hostnames to IP addresses. While external DNS queries would still succeed via forwarding or root hints, internal name resolution would fail, preventing access to internal resources.