Cisco Umbrella Blocking Sites -

Cisco Umbrella is a cloud-delivered security platform that provides DNS-layer security, secure web gateway (SWG), firewall, and cloud access security broker (CASB) capabilities. Its primary blocking mechanism works at the , preventing users from resolving malicious or policy-violating domain names before an HTTP connection is ever made.

When a site is blocked by Umbrella, the user sees:

If the returned IP is 146.112.255.46 or 146.112.255.47 , Umbrella is blocking it. cisco umbrella blocking sites

From an affected machine:

– Plain page stating: “This site is blocked due to a security policy. Your request was denied by Cisco Umbrella.” (Includes block reason, destination, policy name, and optional admin contact.) Cisco Umbrella is a cloud-delivered security platform that

For real‑time debugging, always check and verify the resolved IP of the domain in question.

If a legitimate business site is being blocked (False Positive), you need to add it to an Allow list. From an affected machine: – Plain page stating:

| Symptom | Likely Cause | |---------|----------------| | Legitimate site blocked | Domain previously used for malware; shared IP with bad site | | Newly registered domain blocked | “Domain Age” security setting (blocks domains < 30 days old) | | CDN or cloud storage blocked | Entire netblock classified as “Dynamic DNS” or “Anonymizer” | | Internal app broken | Umbrella resolving internal domain to public block page (split-DNS issue) | | Block page appears for some users but not others | Identity-based policy or different Umbrella configurations |

Cisco Umbrella blocks sites based on specific security and content policies configured by an organization’s IT department. There are three primary reasons a site might be unreachable: Security Risks

If a site is blocked because Umbrella thinks it is Malware or Phishing, but you are certain it is safe: