CCNA Questions

802.1w is the also called Rapid Spanning Tree Protocol. It is not enabled by default on Cisco switches, but it is a better STP to run since it has all the fixes that the Cisco extensions provide with 802.1d

The physical layer takes frames from the Data Link layer and encodes the 1s and 0s into a digital signal for transmission on the network medium.

The Data Link layer is responsible for the framing of data packets.

The Spanning Tree Protocol (STP) was designed to stop layer 2 loops. All Cisco switches have the STP on by default.

PPPoE  or  PPPoA

The following are the different types of VPNs :

PPTP ( Point to Point Tunnel protocol ) VPN : Most commonly used VPN. PPTP is a method for implementing virtual private networks. PPTP uses a control channel over TCP and a GRE tunnel operating to encapsulate PPP packets.

Site-to-Site VPN : Site-to-site VPN is a type of VPN connection that is created between two separate locations. Site-to-site VPN can be intranet based or extranet based. 

Intranet-based site-to-site VPN is created between an organization's propriety networks, while extranet-based site-to-site VPN is used for connecting with external partner networks or an intranet.

L2TP ( Layer Two Tunneling Protoco) VPN : L2TP is an extension of the Point-to-Point Tunneling Protocol (PPTP) used by an Internet service provider (ISP) to enable the operation of a virtual private network over the Internet.

IPsec (Internet Protocol Security) : IPsec is a framework for a set of protocols for security at the network or packet processing layer of network communication.

SSL (Secure Sockets Layer) VPN : SSL  is a form of VPN that can be used with a standard Web browser. In contrast to the traditional Internet Protocol Security (IPsec) VPN, an SSL VPN does not require the installation of specialized client software on the end user's computer. 

MPLS (Multiprotocol Label Switching) VPN : MPLS is a protocol for speeding up and shaping network traffic flows. 

Hybrid VPN : A hybrid VPN combines Multiprotocol Label Switching (MPLS) and Internet protocol security (IPsec)-based VPNs. 

The Session layer of the OSI model offers three different modes of communication : Simplex, half duplex, and full duplex.

The loop back address with IPv4 is 127.0.0.1 . With IPv6, that address is ::1