DNS (Domain Name System) records are essential components of the internet that translate human-readable domain names (like example.com) into machine-readable IP addresses (like 192.0.2.1). They act as a directory for the internet, ensuring that when someone types a domain name into their browser, they are directed to the correct server hosting the website or service.
DNS records are stored on DNS servers and are managed through your domain registrar or hosting provider. Each record has a specific purpose, such as pointing your domain to a server, managing email routing, or providing security features.
Key Terms in DNS Records
Here’s a breakdown of the terms you mentioned:
1. Name
- What it is: The domain name or subdomain that the DNS record applies to.
- Example:
- For
example.com, the name could be@(represents the root domain) orwww(represents thewww.example.comsubdomain). - For a subdomain like
blog.example.com, the name would beblog.
- For
2. Type
- What it is: The type of DNS record, which determines its purpose.
- Common Types:
- A Record: Maps a domain or subdomain to an IPv4 address (e.g.,
example.com→192.0.2.1). - AAAA Record: Maps a domain or subdomain to an IPv6 address (e.g.,
example.com→2001:0db8:85a3::8a2e:0370:7334). - CNAME Record: Creates an alias for one domain to another (e.g.,
www.example.com→example.com). - MX Record: Specifies the mail server responsible for receiving email for the domain (e.g.,
example.com→mail.example.com). - TXT Record: Stores text-based information, often used for verification, SPF, DKIM, or DMARC records.
- NS Record: Specifies the authoritative name servers for the domain (e.g.,
example.com→ns1.examplehosting.com). - SOA Record: Contains administrative information about the domain, such as the primary name server and email of the domain administrator.
- SRV Record: Specifies the location of a specific service (e.g., VoIP, messaging).
- A Record: Maps a domain or subdomain to an IPv4 address (e.g.,
3. Address/Value
- What it is: The data or destination associated with the DNS record.
- Examples:
- For an A Record, this would be an IPv4 address (e.g.,
192.0.2.1). - For a CNAME Record, this would be the target domain (e.g.,
example.com). - For an MX Record, this would be the mail server address (e.g.,
mail.example.com).
- For an A Record, this would be an IPv4 address (e.g.,
4. Distance/Prio (Priority)
- What it is: Used primarily in MX Records to define the priority of mail servers. Lower numbers indicate higher priority.
- Example:
- If you have two MX records:
mail1.example.comwith a priority of10.mail2.example.comwith a priority of20.
- Emails will be sent to
mail1.example.comfirst, and if it’s unavailable, tomail2.example.com.
- If you have two MX records:
5. TTL (Time to Live)
- What it is: The amount of time (in seconds) that a DNS record is cached by DNS resolvers before it needs to be refreshed.
- Purpose: A lower TTL means changes to DNS records propagate faster, but it increases the load on DNS servers. A higher TTL reduces server load but delays updates.
- Example: A TTL of
3600means the record is cached for 1 hour.
6. Service
- What it is: Typically used in SRV Records to specify the service type and protocol (e.g.,
_sip._tcpfor SIP over TCP). - Example:
- An SRV record for a VoIP service might look like:
_sip._tcp.example.com→5060(port) andsipserver.example.com(target).
- An SRV record for a VoIP service might look like:
Example DNS Records
Here’s an example of how these terms come together in a DNS record:
| Name | Type | Address/Value | Distance/Prio | TTL | Service |
|---|---|---|---|---|---|
| @ | A | 192.0.2.1 | – | 3600 | – |
| www | CNAME | example.com | – | 3600 | – |
| @ | MX | mail.example.com | 10 | 3600 | – |
| _sip._tcp | SRV | 5060 sipserver.example.com | 10 | 3600 | SIP over TCP |
| @ | TXT | “v=spf1 include:_spf.example.com ~all” | – | 3600 | – |
Why Are DNS Records Important?
- Website Accessibility: Ensures users can access your website by resolving your domain name to the correct IP address.
- Email Delivery: MX records ensure emails are routed to the correct mail servers.
- Security: TXT records (like SPF, DKIM, and DMARC) help prevent email spoofing and phishing.
- Service Discovery: SRV records help locate specific services (e.g., VoIP, messaging).