Bài giảng Network+ Certification - Chapter 10, TCP/IP Applications

Chapter 10, TCP/IP Applications |1| Chapter Overview A. TCP/IP Services B. TCP/IP Utilities Chapter 10, Lesson 1 TCP/IP Services 1. DHCP A. DHCP origins 1. TCP/IP configuration is a complex issue because every computer must have a unique IP address. 2. You must keep track of the assigned IP addresses to ensure that no duplication occurs. |2| 3. There have been several automated TCP/IP configuration solutions over the years, including a. Reverse Address Resolution Protocol (RARP) b. Bootstrap Protocol (BOOTP) c. DHCP |3| 4. RARP a. Uses the same message format as Address Resolution Protocol (ARP) b. Essentially the opposite of ARP c. Designed for diskless workstations with no means of storing Internet Protocol (IP) addresses d. Not suitable for today’s networks because it supplies only an IP address, no other TCP/IP configuration parameters e. No longer used |4| f. An RARP client broadcasts its hardware address to an RARP server and receives an IP address in return. |5| 5. BOOTP a. Still used occasionally b. Can furnish a client with an IP address plus all of the other required TCP/IP configuration parameters, including IP address, subnet mask, default gateway, and DNS server addresses c. A diskless workstation can also download an executable boot file from a BOOTP server by using the Trivial File Transfer Protocol (TFTP). d. Disadvantages: (1) You must configure the server with the IP address and all other configuration parameters for each client. (2) No mechanism to automatically assign an IP address to a client (3) No mechanism to prevent IP address duplication due to administrator error |6| 6. DHCP 2 Outline, Chapter 10 Network+ Certification, Second Edition a. Addresses the shortcomings of RARP and BOOTP b. Dynamically allocates IP addresses from a pool (called a scope) c. Reclaims unused addresses d. Prevents duplicate address assignments e. Supplies all TCP/IP configuration parameters B. DHCP standards 1. Based on public BOOTP standards 2. Defined in Request for Comments (RFC) 2131 and RFC 2132 3. Published as an open TCP/IP standard C. DHCP architecture |7| 1. Has three components: client, server, and protocol 2. DHCP client a. Integrated into the TCP/IP implementation in most operating systems (1) Usually integrated into the networking client, even if the operating system does not explicitly call it DHCP b. Activated in Windows 2000 by selecting Obtain An IP Address Automatically 3. DHCP server a. An application that processes requests from DHCP clients b. Implemented on most server operating systems, including Windows 2000, Microsoft Windows NT, Novell NetWare, and UNIX 4. DHCP protocol a. Used for communications between clients and servers |8| 5. DHCP supports three types of IP address allocation: manual, automatic, and dynamic. |9| 6. Manual allocation a. You assign a specific IP address to a computer in the DHCP server and the server provides that address to the computer when it is requested. b. Functional equivalent of BOOTP address assignment c. Most labor intensive d. Provides permanent IP address assignments for computers that need them, such as Internet servers e. Using DHCP instead of manual configuration for permanent assignments prevents addresses from being duplicated. |10| 7. Automatic allocation a. The DHCP server supplies clients with IP addresses taken from a common pool of addresses, and the clients retain the assigned addresses permanently. b. Suitable for networks where computers are rarely moved to other subnets c. Minimizes network traffic generated by DHCP |11| 8. Dynamic allocation a. Enables administrators to add, remove, and relocate computers Outline, Chapter 10 3 Network+ Certification, Second Edition b. The DHCP server uses a pool of addresses to lease IP addresses to clients. (1) The client must periodically renew the lease or else the address returns to the pool for reallocation. c. Completely automates the TCP/IP configuration process D. DHCP message format 1. All DHCP traffic uses a single message format. 2. DHCP messages are carried in User Datagram Protocol (UDP) packets. 3. DHCP uses well-known port number 67 at the server and port number 68 at the client. |12| 4. DHCP message fields a. op (1 byte). Specifies whether the message originated at a client or a server b. htype (1 byte). Specifies the type of hardware address in the chaddr field c. hlen (1 byte). Specifies the length of the hardware address in the chaddr field, in bytes d. hops (1 byte). Specifies the number of routers in the path between the client and the server e. xid (4 bytes). Contains a transaction identifier used to associate requests and replies f. secs (2 bytes). Specifies the elapsed time (in seconds) since the beginning of an address allocation or lease renewal process g. flags (2 bytes). Indicates whether DHCP servers and relay agents should use broadcast transmissions to communicate with a client instead of unicast transmissions h. ciaddr (4 bytes). Contains the client computer’s IP address when it is in the bound, renewal, or rebinding state i. yiaddr (4 bytes). Contains the IP address being offered to a client by a server j. siaddr (4 bytes). Specifies the IP address of the next server in a bootstrap sequence (1) Used only when the DHCP server supplies an executable boot file to a diskless workstation k. giaddr (4 bytes). Contains the IP address of a DHCP relay agent located on a different network, when necessary l. chaddr (16 bytes). Contains the hardware address of the client system, using the type and length specified in the htype and hlen fields m. sname (64 bytes). Contains either the host name of the DHCP server or overflow data from the options field n. file (128 bytes). Contains the name and path to an executable boot file for diskless workstations o. options (variable). Contains a series of DHCP options, which specify the configuration parameters for the client computer 5. DHCP options 4 Outline, Chapter 10 Network+ Certification, Second Edition a. DHCP messages carry all of a client’s configuration parameters in the options field. b. The options field can contain multiple options, each of which consists of three subfields. |13| 6. DHCP option subfields a. Code (1 byte). Specifies the function of the option b. Length (1 byte). Specifies the length of the data field c. Data (variable). Contains information specific to the option type 7. DHCP Message Type option a. Required in all DHCP messages b. Specifies the function of the message |14| 8. DHCP Message Type values a. 1—DHCPDISCOVER. Used by clients to request configuration parameters from a DHCP server b. 2—DHCPOFFER. Used by servers to offer IP addresses to requesting clients c. 3—DHCPREQUEST. Used by clients to accept or renew an IP address assignment d. 4—DHCPDECLINE. Used by clients to reject an offered IP address e. 5—DHCPACK. Used by servers to acknowledge a client’s acceptance of an offered IP address f. 6—DHCPNAK. Used by servers to reject a client’s acceptance of an offered IP address g. 7—DHCPRELEASE. Used by clients to terminate an IP address lease h. 8—DHCPINFORM. Used by clients to obtain additional TCP/IP configuration parameters from a server E. DHCP communications |15| 1. Address assignment process a. The DHCP client broadcasts DHCPDISCOVER messages as the system boots. (1) The client is now said to be in the init state. b. DHCP servers receiving the broadcasts respond with a DHCPOFFER message containing an IP address and other configuration parameters. (1) The client might receive offers from multiple servers. c. The client selects one of the offered IP addresses and broadcasts a DHCPREQUEST message that (1) Informs the server that the client is accepting the offer (2) Informs the other servers that their offers are being refused d. Upon receiving the DHCPREQUEST message, the server commits the offered IP address to that client by adding it to the DHCP server database. (1) The client’s lease is identified using a lease identification cookie, which is a combination of the client’s hardware address and the offered IP address. Outline, Chapter 10 5 Network+ Certification, Second Edition e. The server transmits a DHCPACK message to the client, completing the process. f. If the server cannot complete the assignment, it sends a DHCPNAK message to the client, and the entire process begins again. g. The client then performs an ARP test to determine if any other computer is using the assigned IP address. (1) If the IP address is already in use, the client sends a DHCPDECLINE message to the server, and the entire assignment process begins again. (2) If the IP address is not in use, the client begins using it and enters the bound state. |16| 2. IP address leasing process a. The address assignment process is the same for all of the allocation methods. (1) For clients using manual allocation or automatic allocation, there is no further DHCP communication after the address assignment. (2) For clients using dynamic allocation, the address is leased for a time interval specified by the server. b. The client must renew the lease on a regular basis to continue using it. c. DHCP address leases are typically measured in days. (1) If addresses are in short supply, a shorter lease interval is warranted. (2) If computers are rarely moved to other subnets, longer lease intervals reduce the amount of traffic generated by DHCP. |17| 3. Lease renewal process a. A bound client enters the renewing state when it reaches the renewal time value, or T1 value. (1) This value is 50 percent of the lease interval, by default. b. While in the renewing state, the client generates DHCPREQUEST messages and transmits then as unicasts to the server. c. The server can respond with (1) A DHCPACK message, which renews the lease and restarts the lease time clock, or (2) A DHCPNAK message, which terminates the lease and forces the client to restart the address assignment process d. If the server does not respond by the time the client reaches the rebinding time value, or T2 value, the client begins transmitting its DHCPREQUEST messages as broadcasts. (1) The T2 value is 85 percent of the lease interval by default. (2) Any server can now respond with a DHCPACK or DHCPNAK message. e. If the lease expires with no response from a server, the client enters the init state again and restarts the address assignment process. 4. Address release 6 Outline, Chapter 10 Network+ Certification, Second Edition a. A client can release a leased IP address at any time by transmitting a DHCPRELEASE message containing its lease identification cookie to the server. b. Microsoft Windows clients can manually release their addresses by using the Ipconfig utility or Winipcfg utility. 2. Host Files A. TCP/IP systems must use IP addresses to communicate. B. To make TCP/IP more user-friendly, you can assign a host name to a computer. 1. A host name is a name that represents a computer. 2. To communicate with another computer, a TCP/IP system must first resolve its host name into its IP address. 3. Name resolution is the process of converting a host name into an IP address. |18| C. In the early days of TCP/IP and the Internet, host names for the entire Internet were stored in a downloadable text file called HOSTS. 1. A HOSTS file is a lookup table containing a list of host names and their equivalent IP addresses. 2. Each computer has its own HOSTS file. 3. As the Internet grew, the HOSTS file became impractical. 4. DNS eventually replaced the HOSTS file. 5. TCP/IP computers still have HOSTS files, which you can use to bypass network-based name resolution mechanisms. 3. DNS |19| A. DNS characteristics 1. Defined in RFC 1034 and RFC 1035 a. Many additional RFCs provide updates and augmentations to DNS. 2. DNS defines a hierarchical namespace for computer networks and provides a service for resolving names into IP addresses. B. The DNS architecture 1. The DNS client implementation found in every computer running TCP/IP is called a resolver. 2. The DNS server determines the IP address associated with the name requested by a resolver and returns it to the client. |20| C. The DNS namespace 1. DNS names consist of a domain name and a host name. a. A domain name consists of two or more words, which identify a network or an organization running a network. b. A host name identifies a specific computer on that network or in that organization. c. Example: in the name www.microsoft.com, www is the name of a particular host in the domain microsoft.com. 2. Domain names on the Internet must be registered to prevent duplication. Outline, Chapter 10 7 Network+ Certification, Second Edition 3. DNS names are read from right to left, with the word furthest to the right representing the top of the domain hierarchy. 4. The right-most word is the top-level domain. a. Example: the top-level domain in www.microsoft.com is com. b. The DNS standards originally included eight top-level domains: com, edu, gov, mil, net, org, int, and arpa, used for different types of organizations. c. The arpa top-level domain is a special case used for reverse (address- to-name) mapping. d. Now there are also numerous international top-level domains that use two-letter abbreviations of the country name. e. Additional top-level domains have also recently been introduced for commercial use. 5. Second-level domains a. The second-level domain is the second word from the right in a DNS name. (1) Example: the second-level domain name in www.microsoft.com is microsoft. b. Organizations and individuals can register second-level domains in some of the top-level domains for their exclusive use. c. The edu, gov, and mil top-level domains are restricted to educational, government, and military organizations, respectively. d. The com, org, and net top-level domains allow anyone to register names in those domains. e. The owner of a second-level domain is free to create any number of subdomains and hosts in that domain. 6. DNS administration a. The two-tiered administrative arrangement for the DNS is similar to that of IP addresses. (1) An administrative body is responsible for registering the network addresses assigned to various organizations. (2) The administrators of the organizations themselves then create the host address assignments. b. Splitting the administrative chores between a central body and the individual registrant makes it possible to keep the DNS namespace updated. D. DNS communications 1. DNS uses a distributed namespace. a. No single server contains a complete listing of all the domains and hosts on the Internet. 2. To resolve a name, a DNS server parses the name and works with one domain level at a time. 3. Every DNS server has the IP addresses of several root-name servers. a. Root-name servers maintain a list of the top-level domains and the IP addresses of the DNS servers that are authoritative for those domains. 8 Outline, Chapter 10 Network+ Certification, Second Edition (1) An authoritative server is the computer that is the final source of information about a particular domain. |21| 4. The DNS name resolution process a. The client sends the name to be resolved to its designated DNS server. b. The server sends a message to a root name server requesting the IP address of the authoritative server for the name’s top-level domain. c. The root-name server responds with the requested address. d. The client’s server sends a message to the top-level domain server, requesting the address of the authoritative server for the second-level domain. e. The top-level server responds with the requested address. f. The client’s server sends a message to the second-level domain server, requesting the IP address of the specific host. g. The second-level server responds with the requested address. h. The client’s server sends a response containing the requested IP address back to the client. E. Reverse name resolution 1. Sometimes it is necessary to resolve an IP address into a name. 2. The DNS namespace is distributed by name, making it impractical to search the entire namespace for a single address. 3. A special domain called in-addr.arpa contains four layers of subdomains that are named using the decimal numbers 0 to 255. a. You can locate any IP address in the in-addr.arpa domain by converting the decimal values of the address’ four bytes into domain names. b. Example: the IP address 192.168.2.6 would be found in the domain name 6.2.168.192.in-addr.arpa. 4. The bytes of the IP address are reversed in the domain name because a. The most significant identifier is first in an IP address b. The top-level domain comes last in a domain name F. DNS resource records 1. The DNS database is stored in units called resource records. 2. There are several types of resource records; the record type indicates the type of information it contains. |22| 3. DNS resource record types a. Start of Authority (SOA). Indicates that the name server is the authoritative source for the domain b. Name Server (NS). Identifies the DNS servers in the domain c. Address (A). Contains a name-to-address mapping for a computer in the domain d. Canonical Name (CNAME). Used to create an alternative (or alias) name for a computer already represented by an Address record e. Pointer (PTR). Contains an address-to-name mapping in in-addr.arpa for a computer in the domain Outline, Chapter 10 9 Network+ Certification, Second Edition f. Mail Exchange (MX). Identifies a computer that is responsible for processing e-mail traffic addressed to the domain 4. In most cases, you must create resource records manually. 5. A relatively new DNS feature called dynamic updates enables computers to send resource record updates to a DNS server automatically. 4. WINS |23| A. WINS characteristics 1. WINS provides a network-based NetBIOS name resolution service. 2. WINS resolves Windows NetBIOS names into IP addresses, in much the same way that DNS resolves domain and host names. a. The NetBIOS namespace is different from that of DNS, but the problem of resolving names is the same. 3. WINS is used only by computers running Windows. a. Windows 2000 and Windows NT both include a WINS server. b. All computers running Windows have WINS clients. c. Windows 2000 uses DNS names instead of NetBIOS names by default, so the WINS server is included only to support computers running versions of Windows earlier than Windows 2000. 4. WINS is one of several NetBIOS name resolution mechanisms included with Windows, so it is not an essential component. a. Without WINS, a computer uses (1) LMHOSTS, a name resolution mechanism that uses a lookup table like the HOSTS file (2) Broadcast name resolution, a system by which computers broadcast a message containing a NetBIOS name and expect the computer using the name to respond with its IP address 5. WINS generates a minimal amount of network traffic. 6. WINS automatically registers client computer names as they connect to the network, eliminating the need for manual record creation. 7. Using multiple WINS servers and configuring them to replicate their information provides fault tolerance for the network. Chapter 10, Lesson 2 TCP/IP Utilities 1. Introduction A. TCP/IP utilities can take different forms, depending on the implementation. B. Some operating systems provide command-line tools; others provide graphical utilities. 2. Ping |24| A. Ping characteristics 1. Most commonly used of the TCP/IP utilities 2. Virtually every TCP/IP implementation includes a version of Ping. 10 Outline, Chapter 10 Network+ Certification, Second Edition 3. Ping implementations a. Windows: PING.EXE b. UNIX: ping c. Novell NetWare: PING.NLM 4. Ping tests the TCP/IP connectivity to another system on the network. a. A successful ping test indicates that (1) The networking hardware in the other computer is functioning properly (2) The protocols as high as the network layer are operational b. If the ping test fails, one or both of the computers is experiencing a problem with its networking hardware or software. 5. Ping transmits a series of ICMP Echo Request packets to the specified destination. a. The receiving system is expected to respond with an equal number of Echo Reply packets. B. Using Ping 1. The syntax for a command-line Ping implementation such as PING.EXE in Windows 2000 is ping target, where target is the name or IP address of another computer on the network. 2. If the target is a DNS or NetBIOS name, the computer resolves it before sending the Echo Request messages. 3. Most ping implementations have command-line switches that allow you to modify the operational parameters of the program, such as a. The number of Echo Request messages it generates b. The amount of data in each message 4. A successful ping test displays information about each of the Echo Request/Reply messages received from the target. |25| a. In Windows 2000, the ping results display shows (1) The IP address of the computer receiving the Echo Requests (2) The number of bytes of data included with each request (3) The elapsed time between the transmission of each request and the receipt of each reply (4) The value of the Time To Live (TTL) field in the IP header 3. Traceroute |26| A. Traceroute characteristics 1. Variant of the Ping program 2. Displays a list of the routers that form the path through the internetwork that packets take to a destination 3. Traceroute implementations a. Windows: TRACERT.EXE b. UNIX: traceroute c. Novell NetWare: IPTRACE.NLM 4. Uses Echo Request and Echo Reply messages, as Ping does Outline, Chapter 10 11 Network+ Certification, Second Edition a. Whereas Ping only indicates that a problem exists, Traceroute modifies the TTL value in each successive Echo Request message. 5. Can be used to troubleshoot network communications problems by specifying the location of the difficulty 6. Packets might take different routes to a given destination. a. There is no guarantee that the route displayed by Traceroute is the same one used by every packet. B. Using Traceroute 1. The syntax for a command-line Traceroute implementation such as TRACERT.EXE in Windows 2000 is tracert target, where target is the name or IP address of another computer on the network. 2. Traceroute procedure a. The First Echo Request sent by the source computer has a TTL value of 1. b. The first router processing the packet changes the TTL value to 0, discards the packet, and transmits an ICMP Time Exceeded error message back to the sender. c. The second Echo Request message has a TTL value of 2. d. The first router forwards the packet. e. The second router decreases the TTL value to 0, discards the packet, and returns a Time Exceeded message. f. The sender proceeds to send additional Echo Request messages with higher TTL values, causing each successive router on the path to the destination to generate a Time Exceeded message. g. The sender uses the error message information to compile a display of the route that packets take to the target destination. 3. Traceroute displays the elapsed time for each set of messages, enabling you to detect intercontinental jumps. 4. Ifconfig and IPCONFIG.EXE A. Ifconfig 1. UNIX program used to configure TCP/IP parameters for network interfaces 2. Running ifconfig with only the interface name parameter displays the current configuration of the interface. |27| B. IPCONFIG.EXE 1. Windows 2000 and Windows NT version of ifconfig a. Does not have the configuration capabilities of ifconfig b. Microsoft Windows 95, Microsoft Windows 98, and Microsoft Windows Me have a graphical version called WINIPCFG.EXE. 2. Displays the configuration information for the computer’s network interfaces 3. Running IPCONFIG.EXE from the command line displays a summary of the computer’s TCP/IP configuration parameters. 4. Running IPCONFIG.EXE with the /all parameter displays a complete listing of the configuration parameters. 12 Outline, Chapter 10 Network+ Certification, Second Edition 5. On Windows 95/98/Me, you run WINIPCFG.EXE from the \Windows folder. C. IPCONFIG.EXE and DHCP 1. On a DHCP client, IPCONFIG.EXE and WINIPCFG.EXE are the easiest way to display the parameters assigned to the computer by the DHCP server. 2. IPCONFIG.EXE and WINIPCFG.EXE also include controls that allow you to release and renew IP addresses obtained through DHCP. a. With IPCONFIG.EXE, you use the command line parameters /release and /renew. b. With WINIPCFG.EXE, you use the Release, Renew, Release All, and Renew All buttons. 5. ARP A. The Address Resolution Protocol (ARP) is a TCP/IP protocol that resolves IP addresses into hardware (Media Access Control, or MAC) addresses. B. ARP stores the hardware addresses it discovers in a cache for a short time (usually 2 to 10 minutes). |28| C. ARP.EXE characteristics 1. ARP.EXE is a Windows command-line utility that allows you to view and modify the contents of the ARP cache maintained by a TCP/IP system. 2. You can use ARP.EXE to add to the cache the hardware addresses of computers you contact frequently, saving time and network traffic during the connection process. a. Addresses that you add to the cache manually are not purged after the usual expiration period. |29| D. Using ARP.EXE 1. ARP.EXE syntax: ARP [-a {ipaddress}] [-n ipaddress] [-s ipaddress hwaddress {interface}] [-d ipaddress {interface}] 2. ARP.EXE parameters a. -a {ipaddress} Displays the contents of the ARP cache entry (1) The optional ipaddress variable specifies the address of a specific cache entry to be displayed. b. -n ipaddress Displays the contents of the ARP cache for a network interface (1) The ipaddress variable identifies the network interface for which you want to display the cache. c. -s ipaddress hwaddress {interface} Adds a new entry to the ARP cache (1) The ipaddress variable contains the IP address of the computer. Outline, Chapter 10 13 Network+ Certification, Second Edition (2) The hwaddress variable contains the hardware address of the same computer. (3) The interface variable contains the IP address of the network interface in the local system for which you want to modify the cache. d. -d ipaddress {interface} Deletes the entry in the ARP cache that is associated with the computer represented by the ipaddress variable (1) The optional interface variable specifies the cache from which the entry should be deleted. 6. Netstat A. Netstat characteristics 1. Netstat is a command-line program that displays information about a. The current network connections of a computer running TCP/IP b. The traffic generated by the various TCP/IP protocols 2. Netstat implementations a. Windows: NETSTAT.EXE b. UNIX: netstat |30| B. Using NETSTAT.EXE 1. NETSTAT.EXE syntax: NETSTAT [interval] [-a] [-p protocol] [-n] [-e] [-r] [-s] 2. NETSTAT.EXE parameters a. interval Refreshes the display every interval seconds until the user aborts the command b. -a Displays the current network connections and the ports that are currently listening for incoming network connections c. -p protocol Displays the currently active connections for the protocol specified by the protocol variable d. -n When combined with other parameters, causes the program to identify computers using IP addresses instead of names e. -e Displays incoming and outgoing traffic statistics for the network interface, broken down into bytes, unicast packets, nonunicast packets, discards, errors, and unknown protocols f. -r Displays the routing table plus the current active connections g. -s Displays detailed network traffic statistics for the IP, ICMP, TCP, and UDP protocols 7. NBTSTAT.EXE A. Windows command-line program that displays information about NetBIOS over TCP/IP connections |31, 32| B. NBTSTAT.EXE syntax: NBTSTAT [-a name] [-A ipaddress] [-c] [-n] [-r] [-R] [-s] [-S] [-RR] C. NBTSTAT.EXE parameters 14 Outline, Chapter 10 Network+ Certification, Second Edition 1. -a name Displays the NetBIOS names registered on the computer identified by the name variable 2. -A ipaddress Displays the NetBIOS names registered on the computer identified by the ipaddress variable 3. -c Displays the contents of the local computer’s NetBIOS name cache 4. -n Displays the NetBIOS names registered on the local computer 5. -r Displays the number of NetBIOS names registered and resolved by the local computer, using both broadcasts and WINS 6. -R Purges the local computer’s NetBIOS name cache of all entries and reloads the LMHOSTS file 7. -s Displays a list of a. The computer's currently active NetBIOS settings (identifying remote computers by name) b. The current status of the remote computers c. The amount of data transmitted to and received from each system 8. -S Displays a list of a. The computer’s currently active NetBIOS settings (identifying remote computers by IP address) b. The remote computers’ current status c. The amount of data transmitted to and received from each system 9. -RR Sends name release requests to WINS, then starts refresh 10. NBTSTAT.EXE command-line parameters are case sensitive. 8. Nslookup A. Command-line utility that enables you to generate DNS Request messages and transmit them to specific DNS servers B. Allows you to test the functionality and the quality of the information on a specific DNS server by specifying it on the command line C. Nslookup implementations 1. Windows 2000 and Windows NT: NSLOOKUP.EXE 2. UNIX: nslookup |33| D. Nslookup syntax: NSLOOKUP DNSname DNSserver E. Nslookup parameters 1. DNSname Specifies the DNS name that you want to resolve 2. 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 F. Running Nslookup without command-line parameters allows you to run it in interactive mode. |34| 9. Telnet A. Provides remote control capabilities B. A Telnet client on one computer connects to the Telnet server on another computer. Outline, Chapter 10 15 Network+ Certification, Second Edition C. Once connected, a user can execute commands on the other system and view the results. 1. Commands executed during a Telnet session run on the Telnet server computer. 2. However, when you use remote file system access, the commands execute on the client computer. D. Designed for use on UNIX systems E. Windows implementations 1. All Windows versions include a Telnet client. 2. Windows 2000 and later versions have a Telnet server. |35| 10. FTP A. FTP is the acronym for File Transfer Protocol. B. Similar to Telnet, but designed to perform file transfers instead of executing remote commands C. You can use FTP to 1. Transfer files between computers 2. Create and remove directories 3. Rename and delete files 4. Manage access permissions D. Designed for UNIX computers E. Has become a mainstay of Internet communications F. All UNIX computers have FTP client and server capabilities. G. All computers running Windows have a command-line FTP client. 1. Windows 2000 and Windows NT servers have an FTP server built into Microsoft Internet Information Services (IIS). 2. Computers running Windows on a local area network (LAN) share files directly, and therefore do not need FTP. H. Many UNIX networks rely on FTP for LAN file transfers. |36| Chapter Summary A. TCP/IP services 1. DHCP assigns IP addresses by using automatic, manual, or dynamic allocation. 2. DNS resolves host and domain names into IP addresses. 3. WINS resolves NetBIOS names into IP addresses. B. TCP/IP utilities 1. Ping tests whether one computer running TCP/IP can communicate with another computer on the network. 2. Traceroute displays the path that packets take through a network to reach their destinations. 3. IPCONFIG.EXE and WINIPCFG.EXE display information about the computer’s TCP/IP configuration and release and renew DHCP IP address assignments. 16 Outline, Chapter 10 Network+ Certification, Second Edition |37| 4. ARP.EXE enables you to view and modify the contents of the ARP cache maintained by a TCP/IP system. 5. Netstat displays information about a computer’s TCP/IP connections and the traffic passing over them. 6. NBTSTAT.EXE displays information about NetBIOS connections and their traffic. 7. Nslookup enables you to transmit DNS requests to specific servers. 8. Telnet provides remote control access to another computer on the network. 9. FTP enables you to manage files and transfer them to and from a remote computer.