DNS

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The Domain Name System (DNS) is a distributed naming system for any computer, device, service, or other resource connected to the internet or a private network. Its primary function is to translate human-friendly domain names into numerical IP addresses needed for locating computer services and devices worldwide. The DNS system works as its own network; if one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.

Name Servers

Name Servers

Name servers manage a massive database that holds the information that tells the internet where a particular site is located. When a domain name is registered, it will need to have at least two name servers configured to resolve the IP address(es) that it maps to.

When managing a domain name with LAMP Host, you will find the Name Servers link in the Domain Manager for your domain. The picture on the right shows a domain using LAMP Host name servers.

If you registered your domain name with LAMP Host, your name servers will be set for your automatically, pointing to ns1.lamphost.net and ns2.lamphost.net.

Changing Name Servers to LAMP Host

If your domain name is registered elsewhere and you would like to use LAMP Host's Name Servers, set your domain to use the following two server names:

  • ns1.lamphost.net
  • ns2.lamphost.net

DNS Propagation

DNS propagation is the amount of time it takes for modifications of a DNS record to propagate, or spread, throughout the entire internet's DNS infrastructure. If DNS caching did not exist, there would be no such thing as DNS propagation; every DNS request would query your name server and get the modifified record instantly. This scenario would greatly increase the traffic and load on your name servers. To lighten the load on the name servers, the designers of DNS implemented DNS caching.

In DNS caching, servers running DNS queries for web requests (DNS resolvers) store, or cache, a copy of the domain's zone the first time the user asks for that domain's records. For a configurable period of time after that, the name server will not be queried for that domain's zone. Instead, it serves DNS requests by referring to the cached zonefile. This behavior significantly reduces load and bandwidth on DNS name servers.

This caching behavior is what causes propagation. As an example, if a DNS resolver caches a domain zone for two hours (7200 sec TTL), and a modification to an IP address in that zone occurs one hour into that two hour period, the resolver will continue to serve wrong DNS information for the next one hour, until the cache period has expired. Once every resolver in the world has cached the latest version of the zone, propagation has ended.

If you know in advance that you will be changing an IP address in your domain's DNS zone, let us know at least 24 hours prior to the expected change at support@lamphost.com. We will set the TTL (Time To Live) values low (300 seconds, or 5 minutes) so that propagation is fast and painless.

One thing to keep in mind: some ISPs do not honor TTLs, and refresh their resolvers' DNS cache once every 24 hours. Lowering TTLs does not reduce propagation time for these resolvers.

Types of DNS Records

A
An A (Address) record is what points your domain name to the static IP address assigned to the piece of hardware (usually a webserver) that your site files exist on.
MX
An MX (Mail eXchange) record points to an email server that’s configured to process mail for that domain. When there are multiple MX records configured, the record uses preference values to specify the routing order where a lower value equals a higher priority.
NS
NS records are records in the DNS database to determine which authorative name servers are used for the domain.
TXT
TXT records hold free form text of any type. A domain name may have many TXT records. The most common uses for TXT records are Sender Policy Framework (see SPF and Greylisting), DomainKeys (DK), and DomainKeys Identified E-mail (DKIM). TXT records historically have also been used to contain human readable information about a server, network, data center, and other accounting information.
CNAME
The value of a CNAME record is always a domain name, and they are often used to create subdomains. CNAME records are useful because they allow you to set up an alias to a server without using its IP address, through a standard domain name.