DNS – Manual

In this article, you will learn:

• What the DNS infrastructure is and how it works
  • DNS servers
  • NSSET
  • Primary, secondary, and authoritative servers
  • DNSSEC
• What DNS records are and how they work
  • Names
  • Types
• Glossary

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DNS infrastructure

DNS stands for Domain Name System. It is a set of data that makes it possible to resolve various requests for a domain, for example the IP address where the website or the email server of the given domain is located.

DNS works on the principle of a tree structure: every request for a domain starts at the root, and the servers of various services redirect it further into the branches until it is resolved. First, the domain extension is evaluated, which is handled by the registry servers. Then the evaluation of the domain itself continues on the DNS servers of the provider for the given domain.

When a query reaches a branch, it evaluates the DNS recordsit finds on the relevant server. These may point to a specific service server or to other DNS servers.

DNS servers

DNS servers are powerful computers whose sole purpose is to store and provide DNS records. Every domain needs at least one DNS server to work properly, but it usually uses 2 or more mutually synchronized DNS servers.

WEDOS uses 4 DNS servers located in different locations:

ns.wedos.net
ns.wedos.cz
ns.wedos.eu
ns.wedos.com

The system of a single operator verifies data synchronization using serial numbers. These numbers differ between different sets of DNS servers, so it is possible to detect, for example, a configuration with DNS servers of multiple providers, which is undesirable.

When you register a new domain, the registrar usually provides you with its own DNS servers. If you transfer a domain (move it from one registrar to another), the DNS servers remain set to the original provider, who may cancel them. 

To set our or other DNS servers for a domain registered with WEDOS, follow the guide Domains – DNS Servers (NSSET).

To set WEDOS DNS servers at another registrar, follow that provider’s guide and set the four DNS servers listed above, or for CZ domains the NSSET WEDOS.

A change of DNS servers takes effect gradually; the storage time of DNS server records is considerably longer than for DNS records. Most changes usually take effect within a few hours. However, some services may still load data from the original DNS servers for up to 48 hours after the change is made.

NSSET

Because it is easy to make a mistake when listing specific DNS servers, some registries support a solution using an NSSET, that is, a set of name servers. Each NSSET has a unique name within the registry, which you enter instead of listing the individual DNS server addresses. 

Our NSSET is named WEDOS.

Primary, secondary, and authoritative DNS servers

The primary DNS server contains the zone file in which the DNS records of the domain are listed. Secondary DNS servers download this information from the primary server and thereby help distribute the load (sometimes further extended by caching DNS servers). Data is transferred using the AXFR protocol.

Authoritative DNS servers form a set of one primary and usually at least one secondary DNS server. They contain authoritative data for the domain, which means they do not query other servers for the value of DNS records.

You can set WEDOS DNS servers as secondary, that is, allow them to download DNS records from other authoritative servers via AXFR. You can find more information in the article DNS – Secondary Servers (AXFR).

DNSSEC

DNSSEC is a technology that prevents foreign DNS data from being injected during a query. You can find more information and a setup guide for domains registered with WEDOS in the article Domains – DNSSEC.

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DNS records

DNS records contain specific data for routing services using domains. They can also contain various settings or verification codes.

You can have DNS records set on the DNS servers of various providers, but only those on the authoritative DNS servers, that is, the ones set for the domain, take effect.

VEDOS automatically creates DNS records for domains that a customer registers with us, or for which a service with a matching domain name is created. You can also create DNS records manually by following the guide DNS – Adding a Domain.

You usually change DNS records manually. If your domain uses WEDOS DNS servers, follow the guide DNS – Domain Records. In some cases, however, you can have DNS set automatically, for example by ticking the relevant option when ordering a service, renaming or Webhosting alias setup, or pointing a domain to an existing WEDOS service.

The system saves all DNS record changes to a history that you can access by following the guide DNS – Record Change History.

DNS record names

When entering DNS records, follow these rules for names:

• If the DNS record applies to the main domain (e.g. domena.tld), leave the name field empty.

• For subdomains (e.g. eshop.domena.tld), enter only the subdomain name (e.g. eshop; if you enter the name eshop.domena.tld, it will apply to the subdomain eshop.domena.tld.domena.tld).

• The name * denotes all subdomains that have no record of their own. If you assign any record to a specific subdomain, records named * stop applying to it, including those of another of type.

DNS record types

There are many types of DNS records, based on which the system recognizes how to handle a given record. WEDOS supports these record types:

• A and AAAA: Point to the IPv4/IPv6 address of a server. This is usually the address of the web server.
• ALIAS: Replaces A and AAAA records with a domain name. It is used for the main domain; for subdomains, CNAME serves a similar function.
• CAA: Allows the issuance of an SSL certificate.
• CNAME: Points a subdomain to an existing domain. It cannot coexist with other records on the given subdomain.
• MX: Routes emails.
• NS: Delegates the DNS of a subdomain.
• SRV and NAPTR: Specify information about the services available on a host, usually in internet telephony.
• SSHFP and TLSA: Extend the security options of a domain.
• TXT: Allows you to enter any text serving as a setting (for example an SPF record to improve email security), or various verifications.

WEDOS DNS does not support a record of type SOA, it replaces it with separate management of the domain’s DNS servers (NSSET).

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Glossary

• Authoritative DNS servers: DNS servers carrying binding information about the given domain, which all devices on the Internet should follow.
• AXFR: A protocol for transferring DNS information.
• Caching DNS server: An auxiliary DNS server that improves the availability of DNS records and relieves the load on the main DNS server.
• Data (DNS record): The value of the DNS record.
• DNS server: A server specialized in storing and providing DNS records.
• DNS record: Data about the routing or settings of a domain or subdomain.
• DNSSEC: A technology that prevents domain abuse by injecting foreign DNS data.
• FQDN: Fully Qualified Domain Name, that is, the complete name of a domain (e.g. wedos.com).
• Glue record: A special record for cases where a DNS server has in its name a domain for which it is authoritative.
• IPv4: A numeric address of a device on the Internet, e.g. 46.28.105.2. It is entered in an A record.
• IPv6: A newer numeric address of a device on the Internet, e.g. 2a02:2b88:1:4::16. It is entered in an AAAA record.
• Root DNS server: One of the 13 basic DNS servers managed by ICANN.
• Name (of a DNS record): The name of the subdomain the record applies to.
• NSSET: A single unique name for an entire set of DNS servers.
• Primary DNS server: The main holder of a domain’s DNS records.
• Reverse record: A special record that makes it possible to derive a domain name from an IP address. You commonly set it up for servers and Cloud.
• Secondary DNS server: A DNS server that downloads DNS records from elsewhere via AXFR.
• TTL (DNS record): Time To Live. The period in seconds for updating the value of a DNS record on the server.
• Type (DNS record): Determines the purpose and the evaluation procedure of a DNS record.

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