Networking with TCP/IP and the Internet

1. Networking with TCP/IP and the Internet

2. Objectives • Discuss additional details of TCP/IP addressing and subprotocols • Comprehend the purpose and procedure for subnetting • Understand the history and uses of BOOTP, DHCP, WINS, DNS, and host files • Employ multiple TCP/IP utilities for network troubleshooting • Understand TCP/IP applications, such as Internet browsers, e-mail, and voice over IP

3. Addressing and Name Resolution • IP Addressing • An IP address is 32 bits in size • Every IP address is grouped into four 8-bit octets • Octets are separated by decimal points • Valid octet numbers range from 0 to 255 and represent a binary address

4. Addressing and Name Resolution • IP Addressing (cont.) • Each address consists of two parts: network and host • The network portion of an address indicates whether the device belongs to a Class A, B, C, D, or E network • Some octet number are reserved for special functions

5. Addressing and Name Resolution • Static address • IP address that is manually assigned to a device • Dynamic address • IP address that is assigned to a device through DHCP • Dotted decimal notation • “Shorthand” convention used to represent IP addresses and make them more easily readable by people

6. Network Classes Figure 11-1: IP addresses and their classes

7. Network Classes • Multicasting • Allows one device to send data to a specific group of devices (not the entire network segment) • New addressing scheme is being developed • IP version 6 (IPV6) will incorporate this new scheme TABLE 11-1 Three commonly used classes of TCP/IP networks

8. Subnetting • Process of subdividing a single class of network into multiple, smaller networks Figure 11-2: IP address before and after subnets

9. Subnetting • Extended network prefix • The combination of an address’s network and subnet information • Subnet mask • Special 32-bit number that, when combined with a device’s IP address, informs the rest of the network about the network class to which the device is on

10. Subnetting Figure 11-3: Subnetted IP address and its subnet mask

11. Subnetting Figure 11-4: Subnetted network connected to the Internet

12. Subnetting Figure 11-5: Network with several subnets

13. Subnetting Figure 11-6: Data traveling over subnets

14. Gateways • Combination of software and hardware that enable two different network segments to exchange data • Every device on a TCP/IP-based network has a defaultgateway • First interprets its outbound requests to other subnets and then interprets its inbound requests from other subnets • Core Gateways • Gateways that make up the Internet backbone

15. Gateways Figure 11-7: Use of default gateways

16. Network Address Translation (NAT) • Technique in which IP addresses are assigned a public IP address by an IP gateway Figure 11-8: NAT through an IP gateway

17. Sockets and Ports • Socket • Logical address assigned to a specific process running on a host computer • The socket’s address combines the host computer’s IP address with the port numberassociated with a process • Port numbers in the range of 0 to 1023 are called well-known ports

18. Sockets and Ports Table 11-2a: Commonly used TCP/IP port numbers

19. Sockets and Ports Table 11-2b: Commonly used TCP/IP port numbers (cont.)

20. Sockets and Ports Figure 11-9: Virtual circuit for the Telnet service

21. Host Names and Domain Name System (DNS) • Host name • Symbolic name that describes a TCP/IP device • Domain • Group of computers that belong to the same organization and have part of their IP addresses in common

22. Host Files • Text file that associates TCP/IP host names with IP addresses • Alias • Nickname for a node’s host name Figure 11-10: An example of a host file

23. Host Files • On a UNIX-based computer a host file is: • Called hosts • Located in the /etc directory • On a Windows 9x computer, a host file: • Is called lmhosts • Must be located in the c:\windows directory in order to be recognized by the operating system

24. Domain Name System (DNS) • Hierarchical way of tracking domain names and their addresses, devised in the mid-1980s Figure 11-11: DNS server hierarchy by geography

25. Domain Name System (DNS) • Resolvers • Hosts on the Internet that need to look up domain name information • Name servers • Servers that contain databases of names and their associated IP addresses • Each name server manages a group of device, collectively known as a zone

26. Configuring DNS Figure 11-12: Internet Protocol (TCP/IP) Properties dialog box in Windows 2000

27. Configuring DNS Figure 11-13: DNS Configuration properties tab

28. DNS Name Space • Name space • Refers to the actual database of Internet IP addresses and their associated names • Every name server holds a piece of the DNS name space • At the highest level of the hierarchy sit the root servers

29. DNS Name Space • Resource record • Element of a DNS database stored on a name server that contains information about TCP/IP host names and their addresses • Address resource record • Type of resource record that maps the IP address of an Internet-connected device to its domain name

30. Bootstrap Protocol (BOOTP) • Service that simplifies IP address management Figure 11-14: The BOOTP process

31. Bootstrap Protocol (BOOTP) • Thanks to BOOTP, a client does not have to remember its own IP address • Therefore, network administrators do not have to go to each workstation on a network and manually assign its IP address • This situation is ideal for diskless workstations

32. Dynamic Host Configuration Protocol (DHCP) • Automated means of assigning a unique IP address to every device on a network • Reasons for implementing DHCP • Reduce the time and planning spent on IP address management • Reduce the potential for errors in assigning IP addresses • Enable users to move their workstations and printers without having to change their TCP/IP configuration • Make IP addressing transparent for mobile users

33. DHCP Leasing Process • Lease • Agreement between DHCP server and client on how long the client will borrow a DHCP-assigned IP address Figure 11-15: DHCP lease agreement

34. Terminating a DHCP Lease • A DHCP lease may expire based on the period established for it in the server configuration • A DHCP lease may be manually terminated at any time from either the client’s TCP/IP configuration or the server’s DHCP configuration • In some instances, a user must terminate a lease • Release • The act of terminating a DHCP lease

35. Windows Internet Naming Service (WINS) • Provides a means of resolving NetBIOS names with IP addresses • WINS offers several advantages • Guarantees a unique NetBIOS name is used for each computer on a network • Support for DHCP • Better network performance

36. Windows Internet Naming Service (WINS) Figure 11-16: Advanced TCP/IP Settings dialog box in Windows 2000

37. Simple Mail Transfer Protocol(SMTP) and Post Office Protocol (POP) • SMTP • Responsible for moving messages from one e-mail server to another • POP • Provides centralized storage for e-mail messages

38. Internet Mail Access Protocol (IMAP) • Mail storage and manipulation protocol that depends on SMTP’s transport system • Developed as a more sophisticated alternative to POP • Most current version is version 4 (IMAP4) • Biggest advantage of IMAP4 over POP relates to the fact users can store messages on the mail server

39. Additional Features of IMAP4 • Users can retrieve all or only a portion of any mail message • Users can review their messages and delete them while the messages remain on the server • Users can create sophisticated methods of organizing messages on the server • Users can share a mailbox in a central location • IMAP4 can provide better security than POP because it supports authentication

40. Hypertext Transport Protocol (HTTP) • Language that Web clients and servers use to communicate • Forms the backbone of the Web • Hypertext Markup Language (HTML) • Language that defines formatting standards for Web documents

41. Hypertext Transport Protocol (HTTP) Figure 11-18: Web client/server transmission using HTTP

42. Packet Internet Groper (PING) • Troubleshooting utility that can verify TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network • An echo request is a signal sent out to another computer • An echo reply is the other computer’s response signal • Process of sending this signal back and forth is known as pinging

43. Packet Internet Groper (PING) Figure 11-19: Example of successful and unsuccessful PING

44. Netstat • Netstat utility display TCP/IP statistics and details about TCP/IP components and connections on a host Figure 11-20: Output of a simple netstat command

45. Nslookup • Allows you to look up the DNS host name of a network node by specifying its IP address, or vice versa Figure 11-21: Output of a simple ns lookup command

46. Traceroute • Uses ICMP to trace path from one networked node to another • Also known as tracert on Windows machines Figure 11-22: Output of a traceroute command

47. Ipconfig • TCP/IP administration utility for use with Windows NT and Windows 2000 operating systems Figure 11-23: Output of an ipconfig command on a Windows 2000 workstation

48. Ifconfig • TCP/IP configuration and management utility used on UNIX systems Figure 11-26: Detailed information available through ifconfig

49. Internet Services • World Wide Web (WWW, or Web) • Collection of internetworked servers that share resources and exchange information according to specific protocols and formats • Browser • Software that provides clients with a simple, graphical interface to the Web

50. World Wide Web • Uniform Resource Locator (URL) • Standard means of identifying every Web page • Unqualified host name • Host name minus its prefix and suffix