This server is essentially a caching name server, but is useful in cases where computers lie behind a firewall and in which only one computer can make DNS queries outside that firewall on behalf of all the internal computers.Īs an administrator of a DNS server, you need to configure several zones. It holds information that it obtains from other authoritative servers and reuses that information until the information expires (as set by the TTL fields).įorwarding name server ( Creating a server that's not authoritative for a zone but that can forward name server requests to other name servers may prove efficient. Although these types of servers don't have authority for any zones, they can prove useful for special purposes:Ĭaching name server ( This type of server simply caches the information it receives about the locations of hosts and domains. Other specialized types of DNS servers are possible as well. You set the expiration time in the time to live (TTL) field, in the nf file (which I describe later). This delegation of servers defines the servers that have authority for the zone.īecause zone records change as you add, remove, or reconfigure the computers in the zone, you assign expiration times for information about your zone. NS records in the parent zone for a domain list the primary and one or more secondary name servers. (You set secondary servers in the NS RR records for the zone in the nf file on the primary.)
As is the case for the primary, DNS considers the secondary's information about the domain that it serves authoritative. Secondary (slave) name server:?This name server gets all information for the domain from the primary. The secondary name server only carries the same authority in that it has received and loaded a complete set of domain information from the primary. The primary is the ultimate source for data about the domain. In response to queries for information about its domains, this server provides that information marked as being authoritative. Primary (master) name server:?This name server contains authoritative information about the domains that it serves. Each domain is typically represented by at least two DNS servers.
A DNS name server primarily translates domain and host names into IP addresses. The basic function of a name server is to answer queries by providing the information that those queries request.
#Linux setting the zone file time manual
For information on the many different ways to set up a DNS server, open the BIND 9 Administrator Reference manual in a Web browser: /usr/share/doc/bind-9.2.2/arm/Bv9ARM.html. The sample DNS server in this section is one created as an example of a DNS server for a home or small office environment. A compromised DNS server can cause requests for host addresses to be directed to a cracker's server. Setting up a DNS server can be a complex and (these days) potentially dangerous undertaking.
#Linux setting the zone file time how to
The example in the "DNS name server example" section later in this chapter describes how to configure both private and public name and IP address records for a domain. Keeping your DNS information correct means that people can access the services that you want to share, and the Internet as a whole works that much better as a result.īesides using your DNS server to help people from the Internet find the public servers in your domain, you can also use DNS to provide name and IP address mapping for computers on your private network. That's where you come in.Īs someone who's setting up a DNS server, you're responsible for managing the host names and IP addresses for the computers in the domain (or domains) for which you're responsible. Domains that individual organizations own and maintain lie below the TLDs.
Below the root server are the Top Level Domains, or TLDs (such as. At the top of this hierarchy is the root server, represented by a dot (".
That database also contains information related to each domain, such as how the domain is organized into zones, where to route mail for that domain, and who to contact with questions associated with the domain.īy setting up a DNS server, you become part of a hierarchy of DNS servers that make up the Internet. The Domain Name System ( DNS) is essentially a distributed database that translates host names into IP addresses (and IP addresses back to host names).
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