Installing and Configuring DNS with NetWare 5

Transcription

1 BY JOHN E. JOHNSTON Installing and Configuring DNS with NetWare 5 A stable TPC/IP environment is absolutely essential if you are planning to convert to a pure TCP/IP environment. NetWare 5 DNS Service can help you create this TCP/IP infrastructure using its two major components: the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP). ONE of the many benefits of NetWare 5 is its ability to access NetWare resources using only the TCP/IP protocol. However, if you are planning to utilize the TCP/IP protocol to access your NetWare resources, you must first implement a rock solid TCP/IP infrastructure. There are two major components needed to develop this TCP/IP infrastructure: the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP). NetWare 5 provides the ability to run both the DNS and the DHCP functions on NetWare 5 server(s). The NetWare 5 DNS and DHCP functions have been incorporated into a single package known as the Novell DNS/DHCP Services. The Novell DNS/DHCP Services are included on the NetWare 5 installation CD-ROM. Even though the DNS and DHCP Services are installed as a single package, you can enable either function independent of the other. For example, you can enable the DNS function while leaving DHCP disabled and vice versa. Both the DNS and the DHCP services are configured and managed using a single interface known as the DNS/DHCP Management Console, which is a Java application that can be run from a Windows 95 or Windows NT workstation. This article will show step-by-step how to install the Novell DNS/DHCP Services on a NetWare 5 server. Additionally, the installation of the DNS/DHCP Management Console will be covered, as well as how to configure and enable the DNS function. A future article will explore the installation and configuration of the NetWare 5 DHCP function. WHAT IS DNS? All hosts on a TCP/IP network are assigned a 32-bit IP address that looks similar to this: While machines have no problem using IP addresses to access computers, humans have trouble remembering all these numbers. DNS provides a method for humans to access different computers using a host name that is much easier to remember than an IP address. The Domain Name System, in its simplest form, is a database that contains host names and their associated TCP/IP addresses. The Internet fully utilizes DNS to locate networks and hosts. Let's take a look at the structure of the Internet DNS to help visualize how DNS will be used on your local and/or wide area networks. THE STRUCTURE OF THE INTERNET DNS The Internet DNS database is structured as an inverted tree. At the top of the tree is the "root domain." Below this root domain are "top-level" domains that divide the DNS into several segments. The top-level domains are as follows:.com Commercial use.edu Educational institutions.gov Governmental agencies.int International organizations.mil Military agencies.net Networking companies, such as ISPs.org Nonprofit organizations Note that there are other top-level domains used in countries outside of the United States. Organizations that connect their networks directly to the Internet must obtain a registered name from the Internic ( For example, a company named "Technical Support Group" might register a name such as tsg.com. Then, if this company implements a Web site, it could be accessed via

2 "tsg.com" is known as a zone name. This company could then implement a DNS name server on their LAN that would contain a database with all of the local nodes. A DNS name server maintains a database of host names and their associated TCP/IP addresses for a specific zone. For instance, the local DNS name server could contain a database of workstations with names such as: Johnjw95.tsg.com Mariahnt.tsg.com Servers could be named similarly to the following: NW500.tsg.com NTServer1.tsg.com Unixssrvr1.tsg.com If your organization is directly connected to the Internet, your ISP will, most likely, offer to maintain your DNS for you on their DNS servers. While this may be a good option for smaller organizations, larger companies will want to maintain their own DNS servers. By maintaining their own DNS servers, larger organizations can add and delete DNS entries without waiting for their ISP to perform the work for them. If your organization is not directly connected to the Internet, you will need to implement and maintain your own DNS server(s). DNS ZONE RECORD TYPES All DNS name servers contain several types of "resource records" (RRs). Each type of RR contains different host information. The following illustrates the most common RR types: SOA: Start of Authority records identify the DNS name server s zone of authority. For example, the DNS server for "The Technical Support Group" would specify that the DNS name server has authority over the tsg.com zone. Every DNS name server must contain an SOA record. NS: Name Server records define the name server(s) for a specific zone. For example, an NS record for "The Technical Support Group" would state that the DNS name server NW500.TSG.COM is used for tsg.com. A: Address records are the most common FIGURE 1: STATEMENTS TO BE ADDED TO THE AUTOEXEC.NCF FILE LOAD TCPIP LOAD 3C90X.LAN SLOT=2 FRAME=ETHERNET_II NAME=3C90X_1_EII BIND IP 3C90X_1_EII addr= mask= gate= DNS records. These records associate a host name with an IP address. MX: Mail Exchange records define the mail system(s) for a DNS zone. DNS/DHCP SERVICES INSTALLATION PREREQUISITES To ensure a successful implementation, you must make sure that the prerequisites defined in this section have been met on your network. Failure to meet these prerequisites can cause problems with your DNS and DHCP services. NetWare 5 provides the ability to run both the DNS and the DHCP functions on NetWare 5 server(s). The NetWare 5 DNS and DHCP functions have been incorporated into a single package known as the Novell DNS/DHCP Services. Install NetWare 5 Support Pack 1 The NetWare 5 server that is to house the DNS and/or DHCP services must at a minimum have the NetWare 5 Service Pack 1 installed. NetWare 5 Service Pack 2 is currently available and should be installed on all NetWare 5 file servers. Service Pack 2 contains all of the fixes contained in Service Pack 1, in addition to the latest software fixes. The NetWare 5 Service Pack 2 can be obtained from the Novell Web site in the Technical Support Minimum Patch List area. Tip: The NetWare 5 Service Pack 2 is rather large (68MB). The Novell Consolidated Support Pack offering supplies a CD-ROM containing the latest Novell service, including the NetWare 5 Support Pack 2 for $39. For more information on the Consolidated Support Pack offering, visit com/csp/. TCP/IP Must be Loaded and Configured Prior to implementing the Novell DNS/DHCP Services on a NetWare 5 server, the file server must have TCP/IP loaded and configured. The statements shown in Figure 1 must be added to the AUTOEXEC.NCF file to load the TCP/IP protocol. You must, of course, replace the NIC adapter name, IP address, mask and gateway parameters to match your environment. Mixed NetWare 5 and NetWare 4.x Considerations If your NDS tree contains both NetWare 5 and NetWare 4 file servers you must make sure that the Master NDS Replica resides on a NetWare 5 server prior to installing the Novell DNS/DHCP Services. Failure to do so will prevent one of the new NDS objects, the DNS-DHCP Locator, from being created. You can use the NDSMGR32.EXE utility to view the location of your Master Replica or to move the Master Replica to another server. INSTALLING THE DNS/DHCP SERVICES SERVER COMPONENTS In this section, I will demonstrate how to install the Novell DNS/DHCP Services on a NetWare 5 file server. After the installation has completed, these services will not be activated. This will allow you to install the services, then come back at a later date to configure and enable the services. As mentioned earlier, you can enable either the DNS or the DHCP services separately if desired. The following steps are required to install the Novell DNS/DHCP Services: 1. Insert the NetWare 5 installation CD-ROM into the file server s CD-ROM drive. 2. Type CDROM at the System Console. This will mount the volume as NETWARE5:.

3 FIGURE 2: CREATING A DNS SERVER OBJECT FIGURE 6: CREATE AN A RECORD AND A PTR RECORD FIGURE 3: SPECIFYING A SERVER AND DOMAIN NAME FIGURE 7: STARTING THE DNS SERVER FIGURE 4: THE COMPLETED DEFINITION OF THE DNS SERVER OBJECT 5. When prompted for the Source Path, browse to the root of the NETWARE5: CD-ROM volume and click on OK. The temporary installation files will be copied, then the Additional Products and Services panel will be displayed. 6. Click on the box next to Novell DNS/DHCP Services, then click on Next. You will then be prompted to log into the NDS as an administrator. FIGURE 5: CREATING A PRIMARY DNS ZONE 3. From the NetWare 5 GUI screen, click on Novell > Install. A list of installed products will be displayed for you. 4. Click on New Product. 7. Next, you will be prompted for a location in your NDS to place several new objects. If your NetWare network is part of a Wide Area Network (WAN), special care must be taken with the NDS objects that are created by the DNS/ DHCP services. If you have followed Novell s NDS design guidelines, you will have a separate NDS partition in each geographic location. Plan to implement a DNS and a DHCP server in each of these geographic locations. Failure to do so will cause a great deal of traffic to be generated on your WAN links as clients request DHCP and DNS services. There are two special NDS objects that are created during the installation of the NetWare 5 DNS/DHCP services that must be accessible by ALL DNS and DHPC servers on your network: the DNS/DHCP Group Object and the DNS/DHCP Locator Object. Novell recommends that an Organi-zational Unit (OU), Country (C) or Locality (L) container object be created near the top of the NDS tree and the DNS/DHCP Group and Locator objects be placed in that container. The partition that is to contain the DNS/DHCP Group and Locator objects should be replicated to all parts of your network. This replication will provide fault tolerance for your DNS and DHCP services. 8. After selecting the NDS location for these objects, click on Finish. The Installation Complete screen will then be displayed. Look closely at this screen, as it may indicate that errors occurred during the installation. The errors are logged in the file SYS:\NI\DATA\NI.LOG.

4 FIGURE 8: CONFIGURING CLIENTS TO USE THE DNS SERVER FIGURE 9: CREATING AN "A" RECORD FIGURE 10: MAKE SURE THE "A" BUTTON IS TURNED ON 9. After the installation has completed, re-start your NetWare 5 server. INSTALLING THE DNS/DHCP MANAGEMENT CONSOLE The DNS/DHCP Management Console is a Java application that runs under Windows 95 or Windows NT Workstation. This Management Console is used to configure and manage the Novell DNS and DHCP services. To install the DNS/DHCP Management Console, perform the following: 1. From a Windows 95 or Windows NT Workstation, log into the NetWare 5 server and map a drive to the SYS: volume. 2. Click on Start > Run > SYS:\PUBLIC\DNSDHCP\SET- UP.EXE. You will be asked if you wish to install the NetWare Administrator snap-in module. This snap-in provides support for the new DNS/DHCP NDS objects and will also allow you to launch the DNS/DHCP Management Console from within the NetWare Administrator program. You should allow the snap-in to be installed. 3. After the installation has completed, an entry will be created in your Windows Start Menu. CONFIGURING DNS Now we are ready to configure DNS using the DNS/DHCP Management Console. In this section we will learn how to create a DNS server object, create a primary DNS zone, start the DNS service, configure clients to use the DNS service and create the reverse DNS lookup function. Create a DNS Server Object The first step in configuring the DNS service is to create the DNS Server object in the NDS tree. To create the DNS Server object, perform the following steps: 1. Click on Start > Programs > DNSDHCP Management Console > DNSDHCP. 2. From the DNS Service Page, click on the Create icon (this is the second icon from the left and looks like a cube). The Create New DNS Record dialog box will be displayed. 3. Select DNS Server, as shown in Figure Click on the browse button next to the Select Server Object box shown in Figure 3. This will allow you to browse your NDS tree and select a NetWare 5 server where the DNS service is to run. In this example, the server name is NW500 and it resides in a NetWare NDS tree named TSG. 5. Enter a host name for this server and a domain name. In this case, the server s name will be nw500.tsg.com, so we entered nw500 as the host name and tsg.com as the domain name, as shown in Figure After specifying the information in the Create DNS Server dialog box, click on Create. After the server has been created,

5 FIGURE 11: CREATING THE IN-ADDR.ARPA DNS ZONE Starting the DNS Server We are now ready to start the DNS service. From the NetWare 5 server that was designated as the DNS server, enter the following command from the System Console prompt: Load named.nlm. You should see a screen similar to the one shown in Figure 7 if your DNS server starts correctly. Tip: After you ve tested your DNS Service, place the "load named.nlm" command in your file server s AUTOEXEC.NCF file so that DNS starts automatically when your file server is restarted. Configuring Clients to use the DNS Server We must configure our client workstations to utilize the NetWare 5 DNS service. To configure Windows 95 and Windows NT Workstations to utilize the DNS server, perform the following: 1. Click on Start > Control Panel > Network > TCP/IP > Properties. 2. Make sure the Enable DNS button is highlighted. 3. Click on the DNS Configuration tab and enter the TCP/IP address of the DNS server. You must also enter a host and domain name, as shown in Figure 8. your DNS/DHCP Management Console screen should look like the one shown in Figure 4. Create a Primary DNS Zone Object Next, we must create the DNS Zone. The following steps are required to accomplish this: 1. From the DNS/DHCP Management Console DNS Service Page, click on the Create icon. The Create New DNS Record dialog box will be displayed. 2. Next, select Zone. The Create Zone dialog box will then be displayed as shown in Figure 5. The default settings in the Create Zone box will be to set up a primary zone. 3. Click on the browse button next to the NDS Context box. This will allow you to browse your NDS and select a context for the new DNS Zone. In most cases, you should select the root of your NDS tree for the DNS Zone context. 4. Enter a Zone Domain Name. In this case, we chose tsg.com as the domain name. Make sure that the Primary button is highlighted under Zone type:. 5. Click on the down arrow next to the Assign Authoritative DNS Server box. You should select the DNS server object created previously. When completed, your screen should look similar to the one shown in Figure Next, click on Create to create the zone. You will receive a message, as shown in Figure 6, reminding you to create an A record and a PTR record. I will explain how to perform these functions later in this article. Creating "A" Records "A" records are the heart of DNS. They are the records that associate a host name with a TCP/IP address. To create an "A" record, perform the following steps from the DNS/DHCP Management Console: 1. From the DNS Service Page, click on the zone you created previously from the left-hand side of the DNS/DHCP Management Console, as shown in Figure 9. The zone name should become highlighted like tsg.com is. 2. Click on the Create icon and the Create New DNS Record dialog box should appear, also as shown in Figure Next, click on Resource Record, then click on OK. The Create Resource Record screen shown in Figure 10 will be displayed. The Domain Name field should be automatically filled in with your Domain zone name. Make sure the button next to "A" is on, then enter the host name and its associated IP address, as shown in Figure Click on Create. Note that you must create an "A" record for every host on your network that you wish to include in your DNS database. Creating the Reverse Lookup IN-ADDR.ARPA Zone (PTR Records) There are some applications that will request from the DNS server the host name of a node on the network by supplying the TCP/IP address of that host. This is the reverse of the normal DNS lookup where an application is looking for a TPC/IP address by supplying a host name. The NetWare DSN server accomplishes this reverse

6 lookup by maintaining a file of pointer (PTR) records. These PTR records contain the TPC/IP address in reverse order and the associated host name. For example, let's say a node on our test network has a TCP/IP address of In order for the reverse lookup DNS function to work, we would need a PTR record with a TCP/IP address of in-addr.arpa. The "in-addr.arpa" is placed on the end of each PTR record automatically by the DNS server. We must create an IN-ADDR.ARPA DNS zone in order for the reverse DNS lookup function to work. To accomplish this, perform the following steps from the DNS/DHCP management Console: 1. Click on the DNS Service tab. 2 Click on the Create toolbar icon. The Create New DNS Record dialog box will be displayed. 3. Click on Zone and the Create Zone dialog box will be displayed. 4. Click on the radio button next to "IN-ADDR ARPA". 5. Click on the browse button next to the NDS Context box. This will allow you to browse your NDS and select a context for the new IN-ADDR ARPA. In most cases, you should select the root of your NDS tree for the DNS Zone context. Tip: You should place the IN- ADDR.ARPA zone in the same NDS context as your Primary NDS zone. 6. In the Zone Domain name field, you must enter the TCP/IP address of the DSN zone. In this example, we are using a class B TCP/IP network. All nodes in this network have an IP address starting with For this example, we will place in the Zone Domain name field. Notice that the Management Console will automatically reverse the TCP/IP address and append the in-addr.arpa for us, as shown in Figure Make sure the Zone Type is set to Primary. 8. Click on the down arrow next to the "Assign Authoritative DNS Server" field and select the DNS server created earlier, then click on Create. Figure 11 shows the completed "Create Zone" dialog box. CONCLUSION The DNS service included with NetWare 5 is much simpler to install and configure than its counterpart in the NetWare/IP product. The DNS service can be configured and managed from a workstation utility rather than from the System Console as with the prior release. The NetWare 5 DNS service also includes support for IP Version 6, which was not discussed in this article. You can also set up a secondary DNS server using the NetWare 5 DNS that will respond to DNS requests in the event that the primary server is disabled. A stable TPC/IP environment is absolutely essential if you are planning to convert to a pure TCP/IP environment. The NetWare 5 DNS Service will help you create this environment. NaSPA member John E. Johnston is the owner of a web development company that specializes in e-commerce. John also performs contract work on Novell, NT and UNIX networks. John can be contacted at johnj@fast.net Technical Enterprises, Inc. For reprints of this document contact editor@naspa.net.