Network+ Guide to Networks Chapter 3: Addressing on Networks

Network+ Guide to Networks Eighth Edition Chapter 3 Addressing on Networks © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a...

Network+ Guide to Networks Eighth Edition Chapter 3 Addressing on Networks © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 1  Objectives (1 of 2) 3.1 Find the MAC address of a computer and explain its function in network communications 3.2 Configure TCP/IP settings on a computer, including I P address, subnet mask, default gateway, and DNS servers 3.3 Explain the purpose of ports and sockets, and identify the ports of several common, network protocols © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.  Objectives (2 of 2) 3.4 Describe domain names and the name resolution process 3.5 Use command-line tools to troubleshoot problems with network addresses © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.  Addressing Overview Four addressing methods: Data Link layer MAC address - 48 bits, written as six hex numbers separated by colons - Also called physical address Network layer IP address - IPv4 addresses have 32 bits and are written as four decimal numbers called octets - IPv6 addresses have 128 bits and are written as eight blocks of hexadecimal number Transport layer port numbers Application layer FQDNs, computer names, and host names - Fully qualified domain name (FQDN)—A unique character-based name © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 4  MAC Addresses Traditional MAC addresses contain two parts: First 24 bits are known as the OUI (Organizationally Unique Identifier) or manufacturer-ID - Assigned by the IEEE Last 24 bits make up the extension identifier or device I D - Manufacturers assign each N IC a unique device I D © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 5  IP Addresses (1 of 2) Static IP addresses are assigned manually by the network administrator Dynamic IP addresses are automatically assigned by a DHCP (Dynamic Host Configuration Protocol) server You’ll learn more about DHCP later in the chapter To view TCP/IP settings on a Windows 10 computer: In Control Panel, open the Network and Sharing Center. Click Change adapter settings Brief explanation of settings: Gateway—Device that nodes use for access to the outside world Subnet mask—Used to indicate what portion of an I P address is the network portion (network ID) and what part is the host portion (host I D) DNS server—Server responsible for tracking computer names and their I P addresses Domain Name System © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 6  IP Addresses (2 of 2) You can use the ipconfig utility in a Command Prompt to find out current T CP/IP settings Two types of IP addresses: IPv4—A 32-bit address IPv6—A 128-bit address Example - PS C:\Users\13309>ipconfig © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 7  IPv4 Addresses (1 of 7) IPv4 addresses 32-bit address organized into four groups of 8 bits each (known as octets) Each of the four octets can be any number from 0 to 255 Some IP addresses are reserved Example of an IPv4 address: 72.56.105.12 00001100 © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 8  IPv4 Addresses (2 of 7) Classful addressing The dividing line between the network and host portions is determined by the numerical range the IP address falls in Classful IPv4 addresses are divided into five classes: Class A, Class B, Class C, Class D, and Class E Classes A, B, and C licensed IP addresses are available for use on the Internet Called public IP addresses A company can use private IP addresses on its private networks IEEE recommends the following IP addresses be used for private networks: 10.0.0.0 through 10.255.255.255 - A few networks/many hosts 172.16.0.0 through 172.31.255.255 - B Neutral 192.168.0.0 through 192.168.255.255 - C few hosts/ many networks © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 9  IPv4 Addresses (3 of 7) Table 3-1 IP address classes Class Network octets* Approximate Approximate number number of possible of IP addresses in each networks network A 1.x.y.z to 126.x.y.z 126 16 million B 128.0.x.y to 191.255.x.y 16,000 65,000 C 192.0.0.x to 223.255.255.x 2 million 254 © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 10  IPv4 Addresses (4 of 7) Classes D and E addresses were not available for general use: Class D begin with octets 224–239 and are used for multicasting Class E begin with octets 240–254 and are used for research Table 3-2 Reserved IP addresses IP address(es) Function 255.255.255.255 Used for broadcast messages by TCP/IP background processes. A broadcast message is read by every node on the network. 0.0.0.0 Currently unassigned 127.0.0.1 through Used for research or can indicate your own computer, in which case 127.255.255.254 it is called the loopback address. 169.254.0.1 through Used to create an A PIPA (Automatic Private IP Addressing) address 169.254.255.254 when a computer configured for D HCP first connects to the network and is unable to lease an IPv4 address from the D HCP server. © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license dist ributed with a certain product or service or otherwise on a password-protected website for classroom use. 11  IPv4 Addresses (5 of 7) Network Address Translation (NAT)—A technique designed to conserve public IP addresses needed by a network Address translation—Process where a gateway device substitutes the private IP addresses with its own public address When these computers need access to other networks or Internet Port Address Translation (PAT)—Process of assigning a TCP port number to each ongoing session between a local host and Internet host IP 10.0.5.125 -> 150.234.5.6 Socket © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 12 IPv4 Addresses (6 of 7) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 13  IPv4 Addresses (7 of 7) Two variations of NAT to be aware of: SNAT (Static (or Source) Network Address Translation)—The gateway assigns the same public IP address to a host each time it makes a request to access the Internet DNAT (Dynamic Network Address Translation)—The gateway has a pool of public address that it is free to assign to a local host when it makes a request to access the Internet © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 14  IPv6 Addresses (1 of 7) An IPv6 address has 128 bits written as eight blocks of hexadecimal numbers separated by colons: For example, 2001:0000:0B80:0000:0000:00D3:9C5A:00CC Each block is 16 bits Leading zeros in a four-character hex block can be eliminated If blocks contain all zeroes, they can be written as double colons (::), only one set of double colons is used in an I P address Therefore, above example can be written two ways: - 2001::B80:0000:0000:D3:9C5A:CC - 2001:0000:B80::D3:9C5A:CC (preferred method because it contains fewest zeroes) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 15  IPv6 Addresses (2 of 7) IPv6 terminology: Link (sometimes called local link)—Any LAN bounded by routers An interface is a node’s attachment to a link Dual stacked—When a network is configured to use both I Pv4 and IPv6 - Tunneling—A method used by I Pv6 to transport IPv6 packets through or over an I Pv4 network Interface ID—The last 64 bits or four blocks of an I Pv6 address that identify the interface Neighbors—Two or more nodes on the same link © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 16  IPv6 Addresses (3 of 7) Types of IPv6 addresses: Unicast address—Specifies a single node on a network - Global unicast address—Can be routed on the Internet - Link local unicast address—Can be used for communicating with nodes in the same link Multicast address—Packets are delivered to all nodes on a network Anycast address—Can identify multiple destinations, with packets delivered to the closest destination © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 17 IPv6 Addresses (4 of 7) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 18  IPv6 Addresses (5 of 7) Table 3-3 Address prefixes for types of IPv6 addresses IP address type Address prefix Notes Global unicast 2000::/3 First 3 bits are always 001 Link local unicast FE80::/64 First 64 bits are always 1111 1110 1000 0000 0000 0000 …. 0000 Unique local unicast FC00::/7 First 7 bits are always 1111 110 blank FD00::/8 First 8 bits are always 1111 1101 Multicast FF00::/8 First 8 bits are always 1111 1111 © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 19  IPv6 Addresses (6 of 7) Auto configuration: IPv6 addressing is designed so that a computer can autoconfigure its own link local I P address Similar to how IPv4 uses an APIPA address Step 1—The computer creates its IPv6 address: Uses FE80::/64 as the first 64 bits (called prefix) Last 64 bits can be generated in two ways: - Randomly generated - Generated from the network adapter’s MAC address Step 2—The computer checks to make sure its IP address is unique on the network © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 20  IPv6 Addresses (7 of 7) Step 3—The computer asks if a router on the network can provide configuration information (message is called a RS or router solicitation) If a router responds with D HCP information, the computer uses whatever information this might be (called a RA or router advertisement) - Such as the IP addresses of DNS server or the network prefix Process is called prefix discovery - The computer uses the prefix to generate its own link local or global I Pv6 address by appending its interface ID to the prefix © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 21  Ports and Sockets (1 of 3) Port numbers—Ensure data is transmitted to the correct process among multiple processes running on the computer Socket—Consists of host’s IP address and the port number of an application running on the host: Colon separates the two values Example—10.43.3.87:23 Port numbers are divided into three types: Well-known ports—0 to 1023 Registered ports—1024 to 49151 Dynamic and private ports—49152 to 65535 © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 22 Ports and Sockets (2 of 3) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 23  Ports and Sockets (3 of 3) Protocols not yet covered: TFTP (Trivial File Transfer Protocol) NTP (Network Time Protocol) LDAP (Lightweight Directory Access Protocol) SMB (Server Message Block) SIP (Session Initiation Protocol) H.323 © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 24  Domain Names and DNS (Domain Name System) (1 of 3) Character-based names are easier to remember than numeric I P addresses Last part of an FQDN is called the top-level domain (TLD) Domain names must be registered with an Internet naming authority that works on behalf of ICANN ICANN restricts what type of hosts can be associated with.arpa,.mil,.int,.edu, and.gov Name resolution is the process of discovering the IP address of a host when you know the FQDN © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 25  Domain Names and DNS (Domain Name System) (2 of 3) Table 3-5 Some well-known top-level domains Domain suffix Type of organization ARPA Reverse lookup domain (special Internet function) COM Commercial EDU Educational GOV Government ORG Noncommercial organization (such as a nonprofit agency) NET Network (such as an ISP) MIL United States military organization BIZ Businesses INFO Unrestricted use © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 26  Domain Names and DNS (Domain Name System) (3 of 3) DNS is an Application layer client-server system of computers and databases made up of these elements: namespace—The entire collection of computer names and their associated IP addresses stored in databases on D NS name servers around the globe name servers—Hold databases, which are organized in a hierarchical structure resolvers—A DNS client that requests information from D NS name servers © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 27  Namespace Databases Each organization that provides host services is responsible for providing and maintaining its own DNS authoritative servers for public access Authoritative server is the authority on computer names and their IP addresses for computers in their domains The domains that the organization is responsible for managing are called a D NS zone © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 28  Name Servers (1 of 4) Four common types of DNS servers: Primary DNS server—The authoritative name server for the organization - Holds the authoritative DNS database for the organization’s zones Secondary DNS server—Backup authoritative name server for the organization Caching DNS server—Accesses the public D NS data and caches the DNS information it collects Forwarding DNS server—Receives queries from local clients but doesn’t work to resolve the queries Any of these server types can co-exist on the same machine © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 29  Name Servers (2 of 4) DNS name servers are organized in a hierarchical structure At the root level, 13 clusters of root server hold information used to locate top- level domain (TLD) servers TLD servers hold information about authoritative servers owned by various organizations © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 30 Name Servers (3 of 4) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 31  Name Servers (4 of 4) Ways the resolution process can get more complex: Caching server typically is not the same machine as the authoritative server - Caching server exists only to resolve names for its own local clients Name servers within a company might not have access to root servers A TLD name server might be aware of an intermediate name server rather than the authoritative name server Two types of DNS requests: Recursive—A query that demands a resolution or the answer “It can’t be found” Iterative—A query where the local server issues queries to other servers - Other servers only provide information if they have it - Do not demand a resolution © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 32  Resource Records in a DNS Database Several types of records, called resource records are kept in a D NS database: A (Address) record—Stores the name-to-address mapping for a host AAAA (Address) record—Holds the name-to-address mapping, the I P address is an IPv6 type IP address CNAME (Canonical Name) record—Holds alternative names for a host PTR (Pointer) record—Used for reverse lookups NS (Name Server) record—Indicates the authoritative name server for a domain MX (Mail Exchanger) record—Identifies a mail server and is used for email traffic SRV (Service) record—Identifies the hostname and port of a computer that hosts a specific network services besides email TXT (Text) record—Holds any type of free-form text © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 33  DNS Server Software (1 of 2) BIND (Berkeley Internet Name Domain)—Most popular D NS server software Open source—The term for software whose code is publicly available for use and modification Microsoft DNS Server—Built-in DNS service in the Windows Server OS For a more secure network: Internal and external DNS queries should be handled by different DNS servers Can use a firewall to filter or block traffic between networks DMZ or demilitarized zone Area between two firewalls © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 34 DNS Server Software (2 of 2) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 35  Troubleshooting Address Problems Event Viewer—One of the first places to start looking for clues when something goes wrong © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 36  Troubleshooting Tools (1 of 12) Command-link tools are a great resource to troubleshoot network problems Some of the most helpful tools: ping ipconfig (Windows only) ifconfig (Linux only) nslookup dig (Linux only) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 37  Troubleshooting Tools (2 of 12) ping (Packet Internet Groper)—Used to verify that TCP/IP is: Installed Bound to the NIC Configured correctly Communicating with the network The ping utility sends out a signal called an echo request to another device (request for a response) Other computer responds in the form of an echo reply ICMP (Internet Control Message Protocol)—Protocol used by the echo request/reply to carry error messages and information about the network © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 38  Troubleshooting Tools (3 of 12) IPv6 networks use a version of ICMP called ICMPv6: ping6—On Linux computers running IPv6, use ping6 to verify whether an IPv6 host is available ping -6—On Windows computers, use ping with the -6 switch to verify connectivity on IPv6 networks For the ping6 and ping -6 commands to work over the Internet, you must have access to the IPv6 Internet © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 39 Troubleshooting Tools (4 of 12) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 40  Troubleshooting Tools (5 of 12) ipconfig—Shows current TCP/IP addressing and domain name information on a Windows computer Use ipconfig/all to see a more complete summary of T CP/IP addressing information © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 41  Troubleshooting Tools (6 of 12) ipconfig—Shows current TCP/IP addressing and domain name information on a Windows computer Use ipconfig/all to see a more complete summary of T CP/IP addressing information © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 42  Troubleshooting Tools (7 of 12) ifconfig—Utility to view and manage TCP/IP settings If your Linux or UNIX system provides a GUI Open a shell prompt, then type ifconfig Table 3-9 Some ifconfig commands ifconfig command Description ifconfig Displays basic TCP/IP information and network information, including MAC address of the N IC ifconfig -a Displays TCP/IP information associated with every interface on a Linux device; can be used with other parameters (see Figure 3-26) ifconfig down Marks the interface, or network connection, as unavailable to the network ifconfig up Reinitializes the interface after it has been taken down (via the ifconfig down command), so that it is once again available to the network man ifconfig Displays the manual pages, called man pages, for the ifconfig command, which tells you how to use the command and about command parameters (similar to the ipconfig /? command in Windows) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 43 Troubleshooting Tools (8 of 12) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 44  Troubleshooting Tools (9 of 12) nslookup (name space lookup)—Allows you to query the D NS database from any computer on a network: To find the host name of a device by specifying its I P address, or vice versa Useful for verifying a host is configured correctly or for troubleshooting D NS resolution problems Reverse DNS lookup—To find the host name of a device whose IP address you know nslookup 69.23.208.74 Two modes: Interactive—To test multiple DNS servers at one time Noninteractive—Test a single D NS server © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 45 Troubleshooting Tools (10 of 12) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 46  Troubleshooting Tools (11 of 12) You can change DNS servers from within interactive mode with the server subcommand and specifying the IP address of the new D NS server To exit nslookup’s interactive mode, enter exit © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 47  Troubleshooting Tools (12 of 12) dig (domain information groper)—Available on Linux and macO S Provides more detailed information than nslookup and uses more reliable sources of information to output its results Table 3-10 Sample dig commands Sample dig commands Description dig google.com Performs a D N S lookup on a domain name dig @8.8.8.8 google.com Specifies a name server in the google.com domain dig @8.8.8.8 google.com MX Requests a list of all A records in the google.com domain on a specific name server dig google.com ANY Requests a list of all record types in the google.com domain dig –x 74.125.21.102 Performs a reverse lookup on a Google I P address man dig Displays the man page for the dig command © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 48  Common Network Issues (1 of 3) Incorrect time Check a domain computer’s time source from a Command Prompt window by entering w32tm /query /source © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 49  Common Network Issues (2 of 3) DHCP issues: If you are getting DHCP errors or if multiple clients are having trouble connecting to the network - Check the settings on your DHCP server - Make sure the DHCP scope is large enough to account for the number of clients the network must support Consider implementing a shorter lease time on larger networks © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 50  Common Network Issues (3 of 3) Network connection configuration issues Common configuration errors: - Incorrect netmask - Incorrect gateway - Duplicate IP address When a computer is struggling to establish a network connection - Check its TCP/IP configuration settings If the computer is not obtaining an I P address and related information from a DHCP server - Static settings might be using the wrong information - Try switching to DHCP © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 51  Chapter Summary (1 of 3) The IANA is an organization responsible for tracking the assignments of domain names, port numbers, and IP addresses MAC addresses contain two parts, are 48 bits long, and are written in hexadecimal numbers separated by colons IP addresses identify nodes at the Network layer The first part of an IPv4 address identifies the network and the last part identifies the host A DHCP scope is a range of addresses to be assigned to clients when they request an IPv4 address A gateway device that stands between a private network and other networks substitutes the private IP address with its own public address when computers need access to other networks or the Internet © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 52  Chapter Summary (2 of 3) IPv6 standards were developed to improve routing capabilities and speed communication over the established IPv4 standards IPv6 addressing is designed so that a computer can autoconfigure its own link local IP address A port number is a number, assigned to a process: TCP and UDP ports ensure that data is transmitted to the correct process among multiple process running on the computer Name resolution is the process of discovering the IP address of a host when its FQDN is known Namespace databases are stored in DNS zone files The most popular DNS server software is BIND © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 53  Chapter Summary (3 of 3) Troubleshooting utilities and tools: Event Viewer, ping, ipconfig, ifconfig (Linux only), nslookup, and dig (Linux only) If your computer is not a member of a domain, you can determine and adjust the time server your computer syncs to when it connects to the Internet Make sure the DHCP scope is large enough to account for the number of clients the network must support If the computer is not obtaining an IP address and related information from a DHCP server: Static settings might be using the wrong information Try switching to DHCP © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 54