Home > Articles > Certification > Other IT

Solaris Name Services

DNS

DNS is not an objective that is covered in depth on the System Administration Certification exam Part II. You need to know the definition of DNS, but a working knowledge of DNS is not required until you take the Sun Certified Network Administrator examination.

The DNS is the name service provided by the Internet for Transmission Control Protocol/Internet Protocol (TCP/IP) networks. It was developed so that workstations on the network could be identified with common names instead of Internet addresses. DNS is a program that converts domain names to their IP addresses. Without it, users would have to remember numbers instead of words to get around the Internet. The process of finding the IP address of a computer by using its host name as an index is referred to as name-to-address resolution or "mapping."

The collection of networked systems that use DNS are referred to as the DNS namespace. The DNS namespace can be divided into a hierarchy of domains. A DNS domain is simply a group of systems. Each domain is supported by two or more name servers: the primary, secondary, or cache-only server. Each domain must have one primary server and should have at least one secondary server to provide backup.

Each server implements DNS by running a daemon called in.named. On the client side, DNS is implemented through the "resolver." The resolver's function is to resolve users' queries. The resolver is neither a daemon nor a single program; rather, it is a set of dynamic library routines used by applications that need to know system names. After the resolver is configured, a system can request DNS service from a name server. If a system's /etc/nsswitch.conf file specifies hosts: dns, the resolver libraries are automatically used. If the nsswitch.conf file specifies some other name service before DNS, such as NIS, then that name service is consulted first for host information, and then only if that name service does not find the host in question are the resolver libraries used.

For example, if the hosts line in the nsswitch.conf file specifies hosts: nis dns, the NIS name service is first searched for host information. If the information is not found in NIS, the DNS resolver is used. Because name services, such as NIS and NIS+, contain only information about hosts in their own network, the effect of a hosts:nis dns line in a switch file is to specify the use of NIS for local host information and DNS for information on remote hosts out on the Internet. If the resolver queries a name server, the server returns either the requested information or a referral to another server.

Name-to-address mapping occurs if a program running on your local system needs to contact a remote computer. The program most likely knows the host name of the remote computer but might not know how to locate it, particularly if the remote system is in another company, miles from your site. To obtain the remote system's address, the program requests assistance from the DNS software running on your local system, which is considered a DNS client.

Your system sends a request to a DNS name server, which maintains the distributed DNS database. The files in the DNS database bear little resemblance to the NIS+ Host Table or even to the local /etc/hosts file, although they maintain similar information: the host names, IP addresses, and other information about a particular group of computers. The name server uses the host name your system sent as part of its request to find or "resolve" the IP address of the remote system. It then returns this IP address to your local system if the host name is in its DNS database.

If the host name is not in that name server's DNS database, this indicates that the system is outside of its authority, or, to use DNS terminology, outside the local administrative domain.

Because maintaining a central list of domain name/IP address correspondences would be impractical, the lists of domain names and IP addresses are distributed throughout the Internet in a hierarchy of authority. A DNS server that maps the domain names in your Internet requests or forwards them to other servers in the Internet is probably within close geographic proximity to your Internet access provider.

In this chapter, I covered all the name service topics that appear on the Certified Solaris Administrator Examination for Solaris 2.6, Part II. Of course, better understanding of the topics will come as you use the products described and become experienced over time. Many large networks that use a name service are heterogeneous, meaning they have more than just Solaris systems connected to it. You need to refer to the vendor's documentation for each particular system type to understand how each different operating system implements name services. You see that most are similar in their implementation, with only subtle differences. As you gain experience, and complete the Solaris Administrator Certification exams, your next goal should be to become certified as a Sun Network Administrator for Solaris. Certification in both fields is valuable for any UNIX system administrator.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020