Digi W manual N f i g u r i n g D N S, About the Domain Name System

Page 65

Chapter 14

C o n f i g u r i n g D N S

About the Domain Name System

This section discusses key concepts of the domain name system.

Purpose of DNS

The domain name system maps domain names to information associated with these names, such as IP addresses.

DNS Components

DNS components include:

•A distributed database consisting of domain names and associated information

•A hierarchical system of domain name servers that maintain the database and use it to respond to requests for information about a particular domain name, such as its IP address

•Domain name resolvers that

—Accept requests from users

—Satisfy information requests by building and submitting properly formulated queries to one or more name servers or by retrieving information from a local host file

—Return information to users

—Cache information for future use

Types of Name Servers

There are two types of name servers in the domain name system:

•Local servers maintain information for resources within a local zone. It is up to individual network administrators to determine the scope of a local zone.

•Root servers maintain information in higher-level domains than do local servers.

Typically, when a user requires information about a domain name, the resolver queries a local server. If local servers cannot provide the information, root servers are queried next.

Naming Conventions

Each node in the domain name system has a globally unique domain name that consists of its own name, which is called a label, and the labels of all superior nodes.

DNS Name Example

Here is an example of a domain name. Note that labels are separated by periods:

mn07.amalgamated.com

In this example, mn07 is part of the higher-level domain called

Chapter 14 Configuring DNS

65

Image 65

Contents Digi TS W Family 9000329B Configuring the IP Address Chapter Configuring WirelessN t e n t s Chapter IntroductionConfiguring the Serial Ports Setting Up RealPortChapter Configuring PPP Chapter Configuring AutoconnectionConfiguring Security Features Configuring IP RoutingConfiguring DNS Configuring the Digi Device for IAIndustrial AutomationConfiguring Snmp Configuring UsersReference and Certifications Configuring Power Over the Serial PortsContents T r o d u c t i o n Setup OverviewSupported Devices About Entering Commands on the Command LineAbout This Guide Other Documents in the LibraryAbout Configuration Methods Configuration Prerequisites N f i g u r i n g W i r e l e s s Configuration ConsiderationsSelect Discover Digi Device from the CD Configuring Wireless Configuring Wireless Configuring Wireless Configuring Wireless N f i g u r i n g t h e I P a d d r e s s Options for Configuring the IP Address and MaskConfiguring the IP Address Using ARP-Ping Configuring the Ethernet Interface from the Command Line Configuring an IP Address using Dhcp and Rarp About RealPort T t i n g U p R e a l P o r tSetting Up RealPort Configuring the Serial Port Settings with the Web Interface Options for Configuring the Serial PortsConfiguring the Serial Port Settings from the Command Line N f i g u r i n g P P P Configuring Inbound PPP ConnectionsConfiguring Outbound PPP Connections Command Line Configuring Inbound PPP Connections ExampleProcedure Sample Use the following table for additional configurations Configuring PPP Common User Scenarios D e m E m u l a t i o nModem Emulation Digi One TS and PortServer TS 2/4 MEI only Serial Device Digi Device Server Modem Emulation Cable SignalsApplication AT Com Digi Device Server Response Mand Originating, Answering, and Disconnecting CallsServer. P represents a one second pause Code Modem Emulation AT Command Set Function ResultATP Function ResultATXn Accepted but ignored There is no Nvram support currently AT+MS Ascii Registers Function Range Units Saved DefaultRegister Function Range Units Saved Default Register Function Range Units Saved Default 17 11h =XON/XOFF &K4 Result Codes Short Long Form Modem Emulation Commands for Configuring Autoconnection by Port or by User Configuring a Port for Autoconnection Web InterfaceConfiguring a User for Autoconnection Web Interface N f i g u r i n g a u t o c o n n e c t i o nConfiguring UDP Multicast Configuring TCP Socket CommunicationClick Serial Ports Click Change ProfileClick Change Profile and select UDP Socket Configuring Autoconnection N f i g u r i n g I P R o u t i n g Configuring Static RoutesConfiguring Dynamic Routes Using RIP Configuring Proxy ARP Configuring IP Routing N f i g u r i n g S e c u r i t y F e a t u r e s Controlling Access to the ConfigurationControlling Access to Inbound Ports Controlling Access to the Command Line Controlling Access to Outbound PortsDevice Required Hardware Firmware Issuing User PasswordsConfiguring SSH Version 2 for Secure Communication Http Controlling Access to ServicesSnmp SSH Configuring Security Features Configuring the User-Defined Protocol Configuring ModbusConfiguring the Digi Device for IA Industrial Automation About the Domain Name System N f i g u r i n g D N SConfiguration Procedures About Snmp and the Device Server Agent N f i g u r i n g S N M PMIB Configuration Procedure Web InterfaceCommon User Features About Configuring UsersFeature Description Set user Field N f i g u r i n g U s e r sClick New User Configuring a User Web InterfaceCommands for Configuring a User Upgrading the Firmware Copying the Configuration to and from a Remote HostResetting Device Server Configuration to Defaults Commands for Resetting the Configuration to Defaults Managing the OS and Configuration Configuring RI Power Serial Power FeatureConfiguring DTR Power DTR on DTR OFF Serial Power TableConfiguring Power Over the Serial Ports Color State Indicates F e r e n c e a n d C e r t i f i c a t i o n sInterpreting the LEDs RJ-45 Pinouts EIA-232 EIA-422/485 EIA-485 Half Full-Duplex Environmental CertificationsDigi Contact Information Digi Contacts Reference and Certifications