Cisco 300-740 Dumps Questions Answers

The error %OPENDNS-3-DNS_RES_FAILURE indicates a failure to resolve DNS queries via Cisco Umbrella. The most common cause of this error is the router lacking DNS resolution capability. To resolve this, the router must be explicitly configured to use Cisco Umbrella’s OpenDNS servers by adding the following to global configuration:

According to the SCAZT guide (Section 1: Cloud Security Architecture, Pages 17–19), Umbrella enforces cloud-based DNS-layer protection, and upstream devices must be properly configured with working DNS name servers to perform redirection and inspection.

The flow data in the exhibit shows multiple short-duration, high-volume HTTPS connections (443/TCP) from IP 10.10.10.10 to multiple destination IPs in the 50.10.10.0/24 network. All flows are 22 seconds long and transfer exactly 1.77M of data. This uniform behavior to a large set of IP addresses strongly indicates a Denial of Service (DoS) pattern, where an internal host (10.10.10.10) is overwhelming external systems in the 50.10.10.0/24 range.

The SCAZT guide (Section 6: Threat Response, Pages 114–117) explains how Secure Cloud Analytics uses NetFlow and behavioral modeling to identify such volumetric threats. Key identifiers include:

Same connection size (1.77M)

Multiple unique peer IPs in a single external subnet

Same destination port and protocol (HTTPS)

Zero TCP connections completed, indicating unacknowledged connections

This matches the behavioral pattern of a DoS originating from an internal host.

Rule 3 allows all traffic (including SSH) from 10.1.0.0/30 during the hours of 18:00–08:00, which directly conflicts with Rule 1 that is intended to deny SSH at those same hours. Since firewall rules are evaluated top-down and Rule 3 allows traffic during the exact period where SSH should be blocked, deleting Rule 3 will allow Rule 1 to apply correctly.

This behavior is explained in SCAZT Section 3 (Network and Cloud Security, Pages 72–75), where rule precedence and time-based evaluation logic are discussed.