QUESTION 20

1. Virtual Private LAN Services:

	a.	Uses Frame Relay
	b.	Operates at layer 3
	c.	Operates at layer 2
	d.	Uses MPLS
	e.	a and b above
	f.	c and d above

2 points

QUESTION 21

1. Big LEO satellite clusters:

	a.	Work at frequencies above 1 GHz.
	b.	offer paging and low-rate messaging services.
	c.	offer voice and positioning services
	d.	a and c above
	e.	all of the above

2 points

QUESTION 22

1. In cellular communication networks:

	a.	Each cell is assigned a set of frequencies that may not be used by any other cell.
	b.	Each cell contains its own base station and antennae.
	c.	adjacent cells can use the same frequencies to make hand-off of mobile users easier.
	d.	Uses high-power transmitters > 1000W.
	e.	Cells sufficiently distant from each other can use the same frequency band.

2 points

QUESTION 23

1. In IPSecv3, tunnel mode:

	a.	requires that one end of the tunnel be a security gateway such as a firewall or router that implements IPsec.
	b.	provides protection primarily for upper level protocols.
	c.	encrypts and optionally authenticates the IP payload but not the IP header.
	d.	All of the above