The third module ‘Internet Routing & Functions’ focuses on the main protocols and functions used in the Internet that you have been using every day to make network connections. The lecture ‘IGP vs. EGP’ is focused on the types and functions of IGPs (Interior Gateway Protocols) and EGPs (Exterior Gateway Protocols). The lecture ‘OSPF’ describes how OSPF (Open Shortest Path First) sets up SPT (Shortest Path Tree) routing paths, which makes your Internet connections more reliable and fast. The lectures ‘ARP’ and ‘NAT’ explains how you have used ARP (Address Resolution Protocol) and NAT (Network Address Translation) to inter-changing IP addresses for access to private networks and how your PC/laptop/smartphone had been finding IP addresses from web host names. The lectures ‘RPC’ and ‘FTP’ describes how RPC (Remote Procedure Call) had been enabling you to make connections to remote computers/servers, and how FTP (File Transfer Protocol) helped you move files from a remote computer/server to your PC/laptop so quickly. The last lecture ‘E-mail’ compares the characteristics of IMAP (Internet Message Access Protocol) and POP3 (Post Office Protocol version 3) and how they operate in serving your all your e-mails.