During scheduled maintenance, a systems administrator notices that production servers can ping their default gateway and other internal subnets, but cannot reach any external IP addresses or hostnames. A tracert 8.8.8.8 shows the first three hops-the core switch, the perimeter firewall's inside interface, and the firewall's outside interface-responding within normal latency. The trace then stops responding at the first upstream router owned by the company's Internet service provider (ISP), and every subsequent probe times out. A branch office that uses a different carrier reports no issues reaching the Internet. No access-control lists, VLANs, or routing tables were changed during the maintenance. Which action should the administrator take NEXT to restore connectivity?
Change the default route on the core router to point to an alternate VLAN.
Contact the ISP to report a suspected circuit outage and request a trouble ticket.
Flush the forward lookup zone on the internal DNS servers.
Roll back the firewall configuration to the pre-maintenance backup.
The trace stops after the firewall's outside interface and fails to progress beyond the ISP's first hop, which indicates the problem is outside the organization's network. Because local routing, VLANs, and DNS are functioning, the most reasonable next step is to open a trouble ticket with the ISP. Rolling back the firewall configuration is unlikely to help-the firewall is already forwarding traffic successfully to the provider. Flushing internal DNS would not solve the inability to reach numeric IP addresses. Changing the core router's default route merely alters the internal path to the same failed circuit and will not restore Internet access while the provider's link is down.
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What is a trace route (tracert) and how does it work?
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Why wouldn't rolling back the firewall configuration resolve this issue?