At which layer of the OSI model does PPP perform?

The command show frame-relay map gives the following output:
Serial 0 (up): ip 192.168.151.4 dlci 122, dynamic, broadcast, status defined, active
Which statements represent what is shown?(Choose three.)

What can be done to Frame Relay to resolve split-horizon issues?(Choose two.)

What are three reasons that an organization with multiple branch offices and roaming users might
implement a Cisco VPN solution instead of point-to-point WAN links? (Choose three.)

Which command is used to enable CHAP authentication, with PAP as the fallback method, on a serial
interface?

What is the result of issuing the frame-relay map ip 192.168.1.2 202 broadcast command?

Which Layer 2 protocol encapsulation type supports synchronous and asynchronous circuits and has
built-in security mechanisms?

Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?

A network administrator needs to configure a serial link between the main office and a remote
location. The router at the remote office is a non-Cisco router. How should the network
administrator configure the serial interface of the main office router to make the connection?

Which PPP subprotocol negotiates authentication options?