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

Record Type Function

Start of Authority (SOA)

Indicates that the name server is the authoritative source for the domain

Name Server (NS)

Identifies the DNS servers in the domain

Address (A) Contains a name-to-address mapping for a computer in the domain

Canonical Name (CNAME)

Creates an alternative (or alias) name for a computer already represented by an Address record

Pointer (PTR) Contains an address-to-name mapping in in-addr.arpa for a computer in the domain

Mail Exchange (MX)

Identifies a computer that is responsible for processing e-mail traffic addressed to the domain

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 ipaddress hwaddress {interface}] [-d ipaddress {interface}]

Parameter Function

-a {ipaddress} Displays the contents of a specific ARP cache entry

-n ipaddress Displays the contents of the ARP cache for a network interface

-s ipaddress hwaddress {interface} 

Adds a new entry to the ARP cache

-d ipaddress {interface} Deletes an entry in the ARP cache

30

Using NETSTAT.EXE Syntax: NETSTAT [interval] [-a] [-p protocol] [-n]

[-e] [-r] [-s] Parameter

Function

interval Refreshes the display every interval seconds

-a  Displays the current network connections and the ports that are currently listening for incoming network connections

-p protocol 

 Displays the currently active connections for the protocol specified by the protocol variable

-n Causes the program to identify computers using IP addresses instead of names

-e  Displays incoming and outgoing traffic statistics for the network interface

-r  Displays the routing table plus the current active connections

-s   Displays detailed network traffic statistics for the IP, Internet Control Message Protocol (ICMP), TCP, and User Datagram Protocol (UDP) protocols

31

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

Parameter

Function

-a name Displays the NetBIOS names registered on the computer identified by the name variable

-A ipaddress 

Displays the NetBIOS names registered on the computer identified by the ipaddress variable

-c  Displays the contents of the local computer's NetBIOS name cache

-n  Displays the NetBIOS names registered on the local computer

-r Displays the number of NetBIOS names registered and resolved by the local computer, using both broadcasts and WINS

32

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

Parameter Function

-R Purges the local computer's NetBIOS name cache of all entries and reloads the LMHOSTS file

-s Displays a list of the computer's currently active NetBIOS settings (identifying remote computers by name), their current status, and the amount of data transmitted to and received from each system

-S Displays a list of the computer's currently active NetBIOS settings (identifying remote computers by IP address), their current status, and the amount of data transmitted to and received from each system

-RR Sends name release requests to WINS, then starts refresh

33

Nslookup Syntax

Syntax: NSLOOKUP DNSname DNSserver

Parameter Function

DNSname Specifies the DNS name that you want to resolve

DNSserver Specifies the DNS name or IP address of the DNS server that you want to query for the name specified in the DNSname variable

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.