Refer to the exhibit.

Cisco NFVIS follows strict security controls. After a fresh deployment:

Thedefault admin credentials are considered insecure.

NFVIS requires the administrator toreset the default password on first login(typically via console or SSH).

Until the password is changed,REST API and web-portal access are denied, and attempts to access the portal or API returnHTTP 401 Unauthorized, even if the default credentials are provided.

This mechanism prevents use of factory-default passwords in production and is explicitly documented as a mandatory post-install step.

The other options are not the cause of a 401 error:

Enabling portal via SSH (B) is not required; HTTPS access is enabled by default once credentials are valid.

Restarting Tomcat (C) would address service availability issues (e.g., 5xx errors), not authentication.

Browser certificates (D) affect trust warnings (e.g., HTTPS certificate errors), not 401 Unauthorized.