1. Client/Server Network Server Hub Client 1 Client 2 Client 3… 7

2. E-Mail The Internet Smtp. a.org mx.b.or g.pop3. b.org Ns.b.o rg To: bob@b.orgbob@b.org From: alice@a.orgalice@a.org Dear Bob. … mx.b.org MX for b.org? To: bob@b.orgbob@b.org From: alice@a.org alice@a.org Dear Bob. … 8

3. Firewall 0001100 1101001 1100101101 0110 Firewall Internet Home Network 9

4. Simple Home Network Setup Internet DSL/Cable Modem Router Computer A Computer BNotebook C 10

5. Example of a Local Area Network (LAN) HUB PRINTER SERVERSERVER Internet 10101010101010 100010101010 101101 0010101110 1110001010101110 0001110101010100110 Internet Sharing Server Mail Server Sharing Resource File Security server 11

6. Simple Peer-to-Peer Network Hub 12

7. Switches Switching Tab Server 13

8. Hub Computer C Computer D USB Net- LinQ Computer A USB HUB USB Net- LinQ 14