Cisco Updated 200-901 Exam Questions and Answers by herbie

A default gateway serves as an access point or IP router that a networked computer uses to send information to a computer in another network or the internet. It is essentially the forwarding node that routes traffic from a local network to other networks. When an IP packet's destination is not within the local network and no specific route is defined in the routing table, the packet is sent to the default gateway.

Firewalls are used to control incoming and outgoing network traffic based on predetermined security rules, primarily by limiting traffic to only the necessary ports for an application.

Port Filtering: Firewalls can block or allow traffic based on port numbers, thus limiting exposure to only those ports required by the application, enhancing security.

Security: This helps to protect the application from unauthorized access and potential attacks by reducing the attack surface.

NETCONF (Network Configuration Protocol) is an IETF standard protocol used for managing network devices. By default, NETCONF operates over the SSH protocol on port 830. This default port is defined to separate NETCONF traffic from other types of SSH traffic, providing a dedicated channel for network configuration tasks.

When authenticating a RESTCONF API session with a router running Cisco IOS XE software, basic authentication is commonly used. Basic authentication involves sending the username and password in the HTTP header encoded in base64 format. This method is straightforward and widely supported, though it is less secure compared to token-based authentication and should be used with HTTPS to ensure the credentials are encrypted in transit.