Knowledge Base

How to Configure DNS on a VDS Server

Correct DNS configuration is important when hosting websites, email, applications, or other internet services on a VDS server.

DNS allows domain names to resolve to IP addresses, enables subdomains such as www, and helps email traffic reach the correct mail servers.

In this guide, we explain the main DNS record types used with VDS servers, including A, AAAA, CNAME, MX, TXT, NS, and PTR records.

What Is DNS?

DNS stands for Domain Name System.

Its primary purpose is to translate human-readable domain names into IP addresses used by servers.

For example:

example.com → 192.0.2.10

When someone enters example.com into a browser, DNS helps determine which IP address should receive the connection.

Why Is DNS Important for a VDS?

A VDS can host multiple services.

For example:

example.com → Website
www.example.com → Website
panel.example.com → Control panel
api.example.com → API service
mail.example.com → Mail server

DNS determines where each hostname should resolve.

Incorrect DNS configuration can cause websites to become unavailable, email delivery to fail, or SSL validation to encounter problems.

Where Are DNS Settings Managed?

DNS records are managed by the provider responsible for your domain's authoritative nameservers.

This may be:

• Your domain registrar
• Your hosting provider
• Cloudflare
• A hosting control panel
• Your own DNS server

The company where you purchased the domain does not necessarily manage its DNS.

What Is a DNS Zone?

A DNS zone contains the DNS records associated with a domain.

A typical zone may include:

A
AAAA
CNAME
MX
TXT
NS

records.

Hosting panels may call this section DNS Management, DNS Zone, Zone Editor, or DNS Records.

What Is an A Record?

An A record maps a hostname to an IPv4 address.

For example:

This results in:

example.com → 192.0.2.10

You can also create records for subdomains:

This allows panel.example.com to resolve to the same VDS.

What Is an AAAA Record?

An AAAA record performs a similar function to an A record but is used for IPv6 addresses.

Only configure an AAAA record when IPv6 is correctly configured on your VDS.

An incorrect IPv6 record may cause connectivity problems for visitors whose systems prefer IPv6.

What Is a CNAME Record?

A CNAME record aliases one hostname to another hostname.

For example:

This allows:

www.example.com

to follow the DNS resolution of the root domain.

A CNAME target should normally be a hostname rather than an IP address.

What Is an MX Record?

An MX (Mail Exchange) record determines which mail server should receive email for a domain.

For example:

The mail.example.com hostname must then resolve appropriately using an A or AAAA record.

MX targets should be hostnames rather than IP addresses.

What Is MX Priority?

When multiple mail servers are available, MX records can use priority values.

For example:

10 mail1.example.com
20 mail2.example.com

A lower numerical value normally represents a higher preference.

What Is a TXT Record?

TXT records publish text-based information through DNS.

They are frequently used for:

• SPF
• DKIM-related data
• DMARC
• Domain ownership verification
• Third-party service verification

The exact value depends on the service you are configuring.

What Is SPF?

SPF helps specify which systems are authorized to send email on behalf of your domain.

SPF policies are published using DNS TXT records.

Incorrect SPF configuration can contribute to authentication failures or email deliverability problems.

Instead of publishing multiple independent SPF policies for the same domain, authorized sending services generally need to be represented within a valid SPF configuration.

What Is DKIM?

DKIM allows outgoing email to be cryptographically signed.

Receiving mail servers can use a public key published in DNS to verify the DKIM signature.

DKIM information is commonly published under a hostname such as:

selector._domainkey.example.com

The required record and value are normally generated by your mail server or email provider.

What Is DMARC?

DMARC provides domain-level policy and reporting related to SPF and DKIM authentication.

It is typically published as a TXT record under:

_dmarc.example.com

DMARC policies should be deployed carefully. Make sure SPF and DKIM are configured correctly before applying strict enforcement policies.

What Is an NS Record?

NS records identify the authoritative nameservers for a DNS zone.

For example:

ns1.example.com
ns2.example.com

Changing nameservers can effectively move DNS management to another DNS infrastructure, making it a broader change than simply modifying an A record.

What Is a PTR Record?

A PTR record is used for reverse DNS (rDNS).

Normal DNS might resolve:

example.com → 192.0.2.10

Reverse DNS can resolve:

192.0.2.10 → server.example.com

PTR records are particularly important for mail servers because receiving systems may inspect the reverse DNS associated with a sending IP address.

Where Is a PTR Record Configured?

PTR records are generally not managed through your normal domain DNS panel.

Reverse DNS for an IP address is usually controlled by the provider that owns or assigns the IP range.

PTR configuration may therefore be available through:

• Your VDS management panel
• IP management settings
• Your hosting provider's technical support

How Should PTR Be Configured for a Mail Server?

If your mail server is:

mail.example.com

and the IP is:

192.0.2.10

a consistent configuration may include:

mail.example.com → 192.0.2.10

and:

192.0.2.10 → mail.example.com

Other mail server settings, including its HELO/EHLO hostname, should also be configured consistently.

What Is TTL?

TTL specifies how long DNS resolvers may cache a DNS record.

TTL is expressed in seconds.

For example:

3600

represents one hour.

Lower TTL values may help cached records refresh more quickly during planned changes, although very low TTL values are not necessary for every configuration.

Why Don't DNS Changes Appear Immediately?

DNS relies heavily on caching.

After changing a DNS record, some resolvers may continue using the previous value until its cached TTL expires.

As a result, some visitors may temporarily reach the old server while others already reach the new one.

This should be considered when migrating services between servers.

How Should DNS Be Managed During a Server Migration?

A typical migration process is:

1. Prepare the new VDS.
2. Transfer the website and database.
3. Test the website on the new server.
4. If appropriate, lower the TTL before the planned migration.
5. Update the A record to the new VDS IP.
6. Keep the old server running temporarily.
7. Monitor DNS resolution.
8. Retire the old server after confirming the migration.

This can help reduce downtime during migration.

Can I Run My Own DNS Server on a VDS?

Yes.

Software such as BIND, PowerDNS, or DNS services included with hosting control panels can be used to run authoritative DNS.

For example, you could operate:

ns1.example.com
ns2.example.com

However, running authoritative DNS requires more than simply creating DNS records.

You must consider:

• DNS server software
• Authoritative zones
• NS records
• Glue records
• Firewall configuration
• UDP and TCP port 53
• Redundancy
• Security
• Monitoring

Creating two nameserver hostnames on the same VDS does not provide true infrastructure redundancy.

What Is a Glue Record?

Glue records may be required when your nameservers are located under the same domain they serve.

For example:

ns1.example.com → 192.0.2.10

If example.com itself uses ns1.example.com as a nameserver, the registrar can publish the nameserver's IP information to avoid a circular DNS dependency.

Depending on the registrar, this feature may be called:

Glue Record

Child Nameserver

Register Nameserver

or:

Host Record

Which Ports Does DNS Use?

DNS commonly uses:

UDP 53

and, when required:

TCP 53

If you operate your own DNS server, the firewall must allow the necessary DNS traffic.

Do not assume that opening only UDP port 53 is sufficient for every DNS operation.

Using Cloudflare DNS with a VDS

If your domain uses Cloudflare nameservers, your DNS records are managed through Cloudflare.

For a typical website, you may configure:

A → @ → VDS IP

and:

CNAME → www → example.com

When Cloudflare proxying is enabled, visitor traffic may pass through Cloudflare before reaching your VDS.

In this configuration, you usually do not need to operate your own authoritative DNS server on the VDS.

How Can I Check DNS Records?

On Windows:

nslookup example.com

can be used to inspect basic DNS resolution.

On Linux or macOS systems where dig is available:

dig example.com

For MX records:

dig MX example.com

For nameservers:

dig NS example.com

What Should I Check When DNS Is Not Working?

Check whether:

• The domain is active.
• The correct nameservers are configured.
• You edited the DNS records at the correct provider.
• The A record points to the correct IP.
• Old or conflicting records exist.
• An incorrect AAAA record exists.
• Cached DNS information is still being used.
• The web server is configured for the domain.
• The firewall permits the required traffic.

If DNS is correct, the issue may be with the web server or application rather than DNS itself.

Common DNS Configuration Mistakes

Common mistakes include:

• Entering the wrong IP address
• Editing records in a DNS panel that is not authoritative
• Leaving conflicting A records
• Creating AAAA records without working IPv6
• Using an IP address directly as an MX target
• Accidentally deleting email-related DNS records
• Changing nameservers without recreating the required DNS zone
• Trying to configure PTR records from the normal domain DNS panel

Frequently Asked Questions

Do I need DNS for a VDS?

You can access a VDS directly using its IP address. However, DNS records are required when you want to use domain names.

What is the difference between A and CNAME?

An A record maps a hostname to an IPv4 address. A CNAME aliases one hostname to another hostname.

Can an MX record point directly to an IP address?

MX targets should be hostnames. That hostname can then resolve to an IP address through A or AAAA records.

Can I change PTR from my domain DNS panel?

Usually not. PTR/reverse DNS is generally managed by the provider responsible for the IP address.

Is UDP port 53 enough for DNS?

DNS commonly uses UDP 53, but TCP 53 is also part of DNS and is required for some operations.

Do I have to run my own nameservers on a VDS?

No. You can use your registrar's DNS, your hosting provider, Cloudflare, or another DNS provider.

Conclusion

DNS configuration on a VDS involves more than simply pointing a domain to an IP address.

A and AAAA records are used for IP resolution, CNAME records create hostname aliases, MX records direct email, TXT records support verification and email authentication policies, and PTR records provide reverse DNS.

For many websites, using an existing DNS provider is sufficient. Operating your own authoritative DNS infrastructure requires additional security, redundancy, and administration.

When using İde Bilişim VDS services, properly planned DNS records help ensure that your websites, email services, and server applications remain accessible and correctly configured.