MCDST : Supporting Users and Troubleshooting a Microsoft Windows XP Operating System Chapter 13: Troubleshoot TCP/IP

Guide to MCDST Objectives Understand basic network configuration under Windows XP Understand the basics of IP address configuration Perform TCP/IP configuration

Guide to MCDST Objectives (continued) Understand name resolution basics Use TCP/IP troubleshooting tools Resolve basic TCP/IP problems

Guide to MCDST Network Connection Under Windows XP A single, multifaceted interface that combines networking access for LAN, Internet, and modem Accessed through Control Panel

Guide to MCDST Network Connection Under Windows XP (continued)

Guide to MCDST Creating New Network Links Network Connections –Used to create and configure network connections Create a new connection command in the Network Tasks list –Starts a wizard that takes the user through the process of establishing new network links

Guide to MCDST Modifying Existing Network Links Existing local area connections –Can be configured by opening the Properties dialog box for a particular object Components of connection objects –Client: Client for Microsoft Networks –Service: QoS Packet Scheduler –Service: File and Printer Sharing for Microsoft Networks –Protocol: Internet Protocol (TCP/IP)

Guide to MCDST Modifying Existing Network Links (continued)

Guide to MCDST Menu Options in Network Connections File: Disable –Prevents selected Connection object from being used to establish a communications link File: Enable –Allows selected Connection object to be used to establish a communications link

Guide to MCDST Menu Options in Network Connections (continued) File: Connect –Initiates the selected Connection object to establish a communications link File: Status –Displays a Status window for the selected Connection object

Guide to MCDST IP Addressing IP addresses –Logical addresses that are 32 bits (4 bytes) long Internet Protocol (IP) –Fast but unreliable Part of the IP address assigned to a computer –Designates which network the computer is on –Represents the host ID of that computer

Guide to MCDST IP Addressing (continued)

Guide to MCDST The Role of Classes Class A address –First octet is used to identify network and three trailing octets are used to identify the hosts Class B address –First two octets identify the network and the second two identify the host Class C address –Use the first three octets for the network portion and the final octet for the host

Guide to MCDST The Role of Classes (continued) Subnet mask –Used to determine which part of an address denotes the network and which part the host Subnet –Can be written as –Can also be written as /16

Guide to MCDST Uniqueness of an IP Address Each IP address must be unique on the Internet If two IP addresses are duplicated, neither machine with that address is able to access the network To define an IP address, you must configure the TCP/IP protocol

Guide to MCDST TCP/IP Configuration Items that you might need to obtain from a network administrator –Unique IP address for computer –Subnet mask for the network to which the computer belongs –Address of the default gateway –Address of one or more DNS servers, to provide IP name resolution services –You might need to provide an address for a WINS server

Guide to MCDST TCP/IP Configuration (continued)

Guide to MCDST TCP/IP Configuration (continued) Assign an IP address to a computer manually or through DHCP DHCP –Used to automatically configure the TCP/IP settings for a computer Default gateway for a computer –Specifies host to which computer should send data that is not destined for the computer’s subnet

Guide to MCDST Name Resolution An essential service for –Moderate- to large-sized networks –Any system (or network) wishing to communicate with the Internet Forms of name resolution –Domain name to IP address –Computer name to IP address

Guide to MCDST The HOSTS File A static file placed on members of a network to: –Provide a resolution mechanism between host names and IP addresses –Used on small networks where the deployment of a DNS server is unwarranted –Used on remote systems to reduce traffic over slow WAN links –Can be used to hard-code important systems, such as mission-critical servers

Guide to MCDST DNS Handles job of translating symbolic name, such as into a corresponding numeric IP address ( ) Can provide reverse lookup services Highly distributed database that organizes IP names into hierarchical domains

Guide to MCDST LMHOSTS File Static file placed on members of a network to provide a resolution mechanism between NetBIOS names and IP addresses Used only on small networks where deployment of a WINS server is unwarranted Each line of an LMHOSTS file contains an IP address followed by the corresponding NetBIOS name

Guide to MCDST WINS Not a true native TCP/IP service An extension added by Microsoft Dynamic service used to replace the static mechanism of the LMHOSTS file

Guide to MCDST Resolving Name Resolution Problems Only troubleshooting task a DST can perform to resolve problems with name resolution is verifying proper configuration of DNS and WINS server addresses –Check contents of the HOSTS or LMHOSTS files –Ping various systems to test for resolution Otherwise, name resolution problems must be forwarded to the network administrator

Guide to MCDST TCP/IP Troubleshooting Tools Ipconfig command line tool –Used to manage and view information related to DHCP and DNS –When used without any parameters, displays the IP address, subnet mask, and default gateway for all network interfaces on local machine

Guide to MCDST TCP/IP Troubleshooting Tools (continued)

Guide to MCDST PING Command Line Tool Uses the Internet Control Message Protocol (ICMP) protocol to inquire if a designated host is reachable on the network Used to request a response from a remote host Provides information about round-trip time required to deliver a message to machine and receive a reply

Guide to MCDST PING Command Line Tool (continued)

Guide to MCDST PING Command Line Tool (continued) Used to test network latency on each intermediary hop between a local source client and a destination Might be helpful as the tool to use after ping, if a failure is detected May be able to indicate last node, system, or hop that responded to echo requests before the communications failure occurred

Guide to MCDST Tracert Command Line Tool Used to determine the path employed by an ICMP echo request message Displays list of all encountered routers between client and target system along with time to live (TTL) field values

Guide to MCDST Tracert Command Line Tool (continued)

Guide to MCDST Nslookup Command Line Tool Used to translate an FQDN into an IP address using DNS Used to verify that a system’s full name is properly registered in DNS Proper syntax to test a system’s registration –nslookup FQDN

Guide to MCDST Nslookup Command Line Tool (continued)

Guide to MCDST ARP Used to associate a logical (IP) address to a physical (MAC) address Command is used to view and modify the contents of the ARP cache

Guide to MCDST The Use of the Repair Button Appears on the Support tab of a connection object’s Status dialog box Can be used to resolve basic problems with DHCP and name resolution caches Can be used as a troubleshooting technique

Guide to MCDST Troubleshooting TCP/IP Problems Use ipconfig from a Command Prompt to view the current TCP/IP configuration If IP address begins with 169, system did not receive an assigned IP address configuration from DHCP

Guide to MCDST Troubleshooting TCP/IP Problems (continued) If IP address is : –Network cable is disconnected –Device driver for the NIC is not loaded –IP address is a duplicate of another system on the same segment Verify that subnet mask is correct Verify that the default gateway, DNS, and WINS addresses are correct

Guide to MCDST Summary Windows XP Professional provides network access primarily by using TCP/IP TCP/IP –Routable –Supports enterprise-level networks –Has been designed to interconnect dissimilar types of computers –An industry-standard protocol that provides easy cross-platform communication –Thorough knowledge is important

Guide to MCDST Summary (continued) Windows XP –Includes a number of applications that utilize TCP/IP and provide Internet connectivity –Can use a wide variety of name resolution solutions –Includes several tools for viewing, altering, and troubleshooting TCP/IP configuration