Chapter Overview

1. Chapter Overview • TCP/IP Services • TCP/IP Utilities

2. Automated TCP/IP Configuration Solutions • Reverse Address Resolution Protocol (RARP) • Bootstrap Protocol (BOOTP) • Dynamic Host Configuration Protocol (DHCP)

3. RARP • Uses the same message format as Address Resolution Protocol (ARP) • Designed for diskless workstations • Supplies an Internet Protocol (IP) address only • No longer used

4. RARP Communications

5. BOOTP • Supplies an IP address and other Transmission Control Protocol/Internet Protocol (TCP/IP) parameters • Can supply an executable boot file using Trivial File Transfer Protocol (TFTP) • Requires you to manually configure parameters for each client • Cannot allocate IP addresses automatically • Cannot prevent IP address duplication

6. DHCP • Addresses the shortcomings of RARP and BOOTP • Dynamically allocates IP addresses from a pool • Reclaims unused addresses • Prevents IP address duplication • Supplies all TCP/IP parameters

7. DHCP Components • Client • Server • Protocol

8. DHCP Address Allocation Types • Manual allocation • Automatic allocation • Dynamic allocation

9. Manual Allocation • The administrator assigns a permanent IP address to the client. • Manual allocation is used for computers that require permanent IP address assignments.

10. Automatic Allocation • The DHCP server assigns the client a permanent IP address chosen from a pool. • Automatic allocation is used on networks where computers are rarely moved to other subnets. • This minimizes DHCP traffic.

11. Dynamic Allocation • The DHCP server leases to the client an IP address chosen from a pool. • The client must periodically renew the lease address. • Unrenewed lease addresses are returned to the pool. • Dynamic allocation allows you to add, remove, and relocate computers.

12. The DHCP Message Format

13. The DHCP Options Field Format

14. DHCP Message Types • 1—DHCPDISCOVER • 2—DHCPOFFER • 3—DHCPREQUEST • 4—DHCPDECLINE • 5—DHCPACK • 6—DHCPNAK • 7—DHCPRELEASE • 8—DHCPINFORM

15. The DHCP Address Assignment Process

16. The IP Address Leasing Process • The address assignment process is the same for all of the allocation methods. • Clients using manual or automatic allocation receive no further communication after the address assignment. • Clients using dynamic allocation lease IP addresses for a time interval specified by the server. • The client must renew the lease on a regular basis to continue using it. • DHCP address leases are typically measured in days. • If addresses are in short supply, a shorter lease interval is warranted. • If computers are rarely moved to other subnets, longer lease intervals reduce the DHCP traffic.

17. The DHCP Lease Renewal Process

18. The HOSTS File • A HOSTS file is a lookup table containing a list of host names and their equivalent IP addresses. • Each computer has its own HOSTS file. • As the Internet grew, the HOSTS file became impractical, and the Domain Name System (DNS) eventually replaced it.

19. DNS Characteristics • Defined in Request for Comments (RFC) 1034 and RFC 1035 • DNS defines • A hierarchical namespace for computer networks • A service for resolving names into IP addresses

20. The DNS Namespace

21. The DNS Name Resolution Process

22. DNS Resource Record Types

23. WINS Characteristics • Is the acronym for Windows Internet Name Service • Is a Network Basic Input/Output System (NetBIOS) name server • Resolves NetBIOS names into IP addresses • Used only by Microsoft Windows computers

24. Ping Characteristics • Supplied with virtually every TCP/IP implementation • Tests connectivity to another TCP/IP system • Syntax: ping target

25. Ping Output (Typical) Pinging cz1 [192.168.2.10] with 32 bytes of data: Reply from 192.168.2.10: bytes=32 time<10ms TTL=128 Reply from 192.168.2.10: bytes=32 time<10ms TTL=128 Reply from 192.168.2.10: bytes=32 time<10ms TTL=128 Reply from 192.168.2.10: bytes=32 time<10ms TTL=128 Ping statistics for 192.168.2.10:Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds:Minimum = 0ms, Maximum = 0ms, Average = 0ms

26. Traceroute Characteristics • Variant of the Ping program • Displays a list of the routers on the path that packets take to a destination • Uses Echo Request and Echo Reply messages, as Ping does • Modifies the Time To Live value in each successive Echo Request message • Can be used to troubleshoot network communications problems by specifying the location of the difficulty

27. IPCONFIG.EXE and WINIPCFG.EXE Characteristics • IPCONFIG.EXE and WINIPCFG.EXE are Windows utilities that display TCP/IP configuration parameters. • Use IPCONFIG.EXE on Microsoft Windows 2000 and Microsoft Windows NT. • Use WINIPCFG.EXE on Microsoft Windows 95, Microsoft Windows 98, and Microsoft Windows Me. • Both utilities can release and renew DHCP IP addresses.

28. ARP.EXE Characteristics • ARP.EXE enables you to view and modify the contents of the ARP cache. • Adding addresses to the ARP cache speeds up the connection process. • Addresses added manually to the ARP cache are not purged.

29. Using ARP.EXE Syntax: ARP [-a {ipaddress}] [-n ipaddress] [-s ipaddresshwaddress {interface}] [-d ipaddress {interface}]

30. Using NETSTAT.EXE Syntax: NETSTAT [interval] [-a] [-p protocol] [-n] [-e] [-r] [-s]

31. Using NBTSTAT.EXE Syntax: NBTSTAT [-a name] [-A ipaddress] [-c] [-n] [-r] [-R] [-s] [-S] [-RR]

32. Using NBTSTAT.EXE (Cont.) Syntax: NBTSTAT [-a name] [-A ipaddress] [-c] [-n] [-r] [-R] [-s] [-S] [-RR]

33. Nslookup Syntax Syntax: NSLOOKUP DNSname DNSserver

34. Telnet • Telnet provides remote control capabilities. • Telnet clients can execute commands on a server and view the results. • Telnet was designed for UNIX systems. • All Windows versions include a Telnet client. • Windows 2000 and later versions have a Telnet server.

35. FTP • You can use the File Transfer Protocol (FTP) to transfer files between computers, create and remove directories, rename and delete files, and manage access permissions. • FTP was designed for UNIX computers. • FTP is the mainstay of Internet communications. • All UNIX computers have FTP client and server capabilities. • All Windows computers have a command-line FTP client. • Windows 2000 and Windows NT servers have an FTP server built into Microsoft Internet Information Services (IIS).

36. Chapter Summary • TCP/IP services • DHCP assigns IP addresses by using automatic, manual, or dynamic allocation. • DNS resolves host and domain names into IP addresses. • WINS resolves NetBIOS names into IP addresses. • TCP/IP utilities • Ping tests whether one computer running TCP/IP can communicate with another computer on the network. • Traceroute displays the path that packets take through a network to reach their destinations. • IPCONFIG.EXE and WINIPCFG.EXE display information about the computer’s TCP/IP configuration, and they release and renew DHCP IP address assignments.

37. Chapter Summary (Cont.) • TCP/IP utilities (Cont.) • ARP.EXE enables you to view and modify the contents of the ARP cache maintained by a TCP/IP system. • Netstat displays information about a computer’s TCP/IP connections and the traffic passing over them. • NBTSTAT.EXE displays information about NetBIOS connections and their traffic. • Nslookup enables you to transmit DNS requests to specific servers. • Telnet provides remote control access to another computer on the network. • FTP lets you manage files and transfer them to and from a remote computer.