Download Full Version 350-701 Cisco Exam

DNS tunneling is a technique that encodes data of other programs and protocols in DNS queries, including data payloads that can be used to control a remote server and applications1. DNS exfiltration is a form of DNS tunneling that allows attackers to extract data from a compromised system by sending encoded DNS requests to a domain under their control2. The direction of the data transfer in DNS exfiltration is outbound, meaning from the victim’s network to the attacker’s network. This is different from inbound, which means from the attacker’s network to the victim’s network, or north-south and east-west, which are terms used to describe the traffic flow between different network segments or zones3. Outbound DNS requests are often allowed by default in many firewalls and network devices, making them an attractive channel for data exfiltration4. However, DNS exfiltration can be detected and prevented by using security solutions that monitor and analyze DNS traffic for anomalies and malicious patterns5.

 1: Improvements to DNS Tunneling & Exfiltration Detection - Cisco Umbrella 2: DNS Exfiltration & Tunneling: How it Works & DNSteal Demo Setup 3: What Is DNS Tunneling? - Palo Alto Networks 4: DNS Data Exfiltration and DNS Tunneling | Vercara 5: DNS Exfiltration: The Light at the End of the DNS Tunnel - site

The purpose of a Denial-of-Service (DoS) attack is to disrupt the normal operation of a targeted system, server, or network by overwhelming it with a flood of internet traffic. This is achieved by utilizing multiple compromised computer systems as sources of attack traffic. The overwhelming amount of traffic can cause the targeted system to slow down significantly or even crash and become unavailable to legitimate users, thereby denying service to intended users.

 GET VPN (Group Encrypted Transport VPN) is a tunnel-less VPN technology that uses a single security association (SA) for all routers in a group. This allows GET VPN to natively support MPLS and private IP networks, without requiring any additional encapsulation or tunneling protocols. GET VPN also supports multicast traffic without GRE, which reduces overhead and improves performance. FlexVPN is a newer VPN solution that covers all VPN types, such as site-to-site, hub and spoke, and remote access. FlexVPN uses IKEv2 for all VPN types, which offers some advantages over IKEv1, such as resiliency and fewer messages. However, FlexVPN requires newer hardware and software versions to support its features. FlexVPN also relies on GRE or static and dynamic point-to-point interfaces to support MPLS and private IP networks, which adds complexity and overhead. Therefore, a benefit of using GET VPN over FlexVPN within a VPN deployment is that GET VPN natively supports MPLS and private IP networks, without requiring any additional encapsulation or tunneling protocols. References:

Group Encrypted Transport VPN (GETVPN)

Introduction to FlexVPN

what is the difference between dmvpn and flexvpn

 The RADIUS CoA feature supports five IETF attributes as defined in RFC 5176. These are:

Event-Timestamp: This attribute indicates the time when the CoA request was generated by the server.

State: This attribute contains a value that is copied from the Access-Accept message that authorized the session.

Session-Timeout: This attribute specifies the maximum number of seconds of service provided to the user before termination of the session or prompt.

Idle-Timeout: This attribute specifies the maximum number of consecutive seconds of idle connection allowed to the user before termination of the session or prompt.

Filter-Id: This attribute identifies the filter list to be applied to the user session.

The RADIUS CoA feature also supports vendor-specific attributes (VSAs) that are defined by Cisco or other vendors. These VSAs can be used to perform additional actions such as port shutdown, port bounce, or security and password accounting. References :=

Some possible references are:

RFC 5176: This document describes the dynamic authorization extensions to RADIUS, including the CoA request and response codes, and the supported IETF attributes.

RADIUS Change of Authorization - Cisco: This document provides the configuration guide for the RADIUS CoA feature on Cisco IOS devices, including the supported IETF and Cisco VSAs.

Supported IETF attributes in RFC 5176 - Ruckus Networks: This document lists the supported IETF attributes and error clause values for the RADIUS CoA feature on Ruckus devices.

V