DNS - Manual

In this article you will learn:

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

---

DNS infrastructure

DNS stands for Domain Name System. It is a set of data files that allow various requests for a domain to be resolved, for example which IP address hosts a website or the email server of a given domain.

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

When a query reaches a branch, it evaluates the DNS records it 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 function properly, but usually uses 2 or more mutually synchronized DNS servers.

WEDOS uses 4 DNS servers located in different places:

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

A single provider's system verifies data synchronization using serial numbers. These numbers differ across different sets of DNS servers, so it is possible to identify, for example, DNS server settings from multiple providers, which is undesirable.

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

If you want to set up our or other DNS servers for a domain registered with WEDOS, follow the guide Domains – DNS servers (NSSET).

If you want to set WEDOS DNS servers at another registrar, set the above-mentioned four DNS servers according to that provider's instructions, or for CZ domains the NSSET WEDOS.

Changing DNS servers happens gradually; the retention period for DNS server records is significantly longer than for DNS records. A large part of the changes usually takes effect within a few hours. However, some services may continue to read data from the original DNS servers for up to 48 hours after the change is entered.

NSSET

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

Our NSSET is named WEDOS.

Primary, secondary and authoritative DNS servers

A primary DNS server contains the zone file with the domain's DNS records. Secondary DNS servers download this information from the primary server and help distribute the load (sometimes further extended by caching DNS servers). Data transfer takes place via the AXFR protocol.

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

You can set WEDOS DNS servers as secondary, allowing them to download DNS records from other authoritative servers via AXFR. More information can be found in the article DNS – Secondary servers.

DNSSEC

DNSSEC is a technology that prevents foreign DNS data from being injected during a query. More information and instructions for setting it up for domains registered with WEDOS can be found in the article Domains – DNSSEC.

---

DNS records

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

You can have DNS records set on DNS servers from different providers, but only those on authoritative DNS servers, i.e. those set for the domain, actually work.

VEDOS automatically creates DNS records for domains that a customer registers with us, or for which they create services with a corresponding domain name. DNS can also be created manually according to 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 when selecting the option in the service order, renaming or setting a Webhosting alias, or pointing the domain to an existing WEDOS service.

All DNS record changes made are stored by the system in a history accessible according to the guide DNS – Record change history.

DNS record names

When entering DNS records, follow these rules for names:

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

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

• The name * indicates all subdomains that do not have their own record. If you assign any record to a specific subdomain, records named * will no longer apply to it, including those of another type.

Types of DNS records

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

• A and AAAA: Point to the server's IPv4/IPv6 address. Usually this is the web server address.
• ALIAS: Replaces A and AAAA records with a domain name. Used for the main domain; for subdomains it serves a similar function to CNAME.
• CAA: Allows issuance of an SSL certificate.
• CNAME: Points a subdomain to an existing domain. It is mutually exclusive with other records on the given subdomain.
• MX: Routes email.
• NS: Delegates DNS subdomains.
• SRV and NAPTR: Specify information about available host services, usually in internet telephony.
• SSHFP and TLSA: Extend domain security options.
• TXT: Allows you to enter any text used as a setting (for example, an SPF record to improve email security), or various verifications.

WEDOS DNS does not support the SOA record type; it is replaced by separate management of the domain's DNS servers (NSSET).

---

Glossary

• Authoritative DNS servers: DNS servers carrying binding information about a 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 makes DNS records more available and reduces the load on the main DNS server.
• Data (of a DNS record): The value of a DNS record.
• DNS server: A server specialized in storing and providing DNS records.
• DNS record: Data about routing or settings for a domain or subdomain.
• DNSSEC: A technology that prevents domain abuse by injecting foreign DNS data.
• FQDN: Fully Qualified Domain Name, i.e. the complete domain name (e.g. wedos.com).
• Glue record: A special record used to handle cases where a DNS server has in its name the domain for which it is authoritative.
• IPv4: A numerical address of a device on the Internet, e.g. 46.28.105.2. It is used in an A record.
• IPv6: A newer numerical address of a device on the Internet, e.g. 2a02:2b88:1:4::16. It is used in an AAAA record.
• Root DNS server: One of the 13 basic DNS servers managed by ICANN.
• Name (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 allows a domain name to be derived from an IP address. You usually set it up for servers and Cloud.
• Secondary DNS server: A DNS server that downloads DNS records from elsewhere via AXFR.
• TTL (of a DNS record): Time To Live. The period in seconds for updating the value of a DNS record on the server.
• Type (of a DNS record): Determines the purpose and evaluation process of a DNS record.