Tag: DNS

CNAME record explained

CNAME record

The CNAME record is one of the first DNS records that you will read about when you are starting with DNS management. It has a very important task to do, showing the true domain name for the subdomains, making it really an essential DNS record. It saves time and makes it easier to manage the DNS.

CNAME explained completely

There are two parts in the CNAME’s name. C stands for canonical, and it wants to show which is the true domain name for the one that you are trying to resolve. The NAME is obvious. It stands for name, as in hostname.

The purpose of the CNAME record is to point one hostname to another. You can point different subdomains to the domain name. That way, you don’t need to add any other records for the subdomain because it will automatically redirect to the domain name.

If you have just a single DNS record for each subdomain, you will have far fewer DNS records, and the administration of your domain will be a lot easier.

CNAME records can be used to point:

www.domain.com to domain.com

blog.domain.com to domain.com

mail.domain.com to domain.com

newyork.domain.com to domain.com

Because of the way the CNAME record works, if the host (subdomain) already has other DNS records like A, MX, etc., you can’t create a CNAME record. And if you first create a CNAME record in the zone, you can’t create any other type of record in that zone.

Inside a CNAME record, you will see:

Host – the name of the subdomain that you want to point to the main domain name.

Type – CNAME.

Points to – the domain name. All of the CNAME records will point to this one.

TTL – time to live for that DNS record.

How to lookup a CNAME record?

If you are on Windows, the easiest and the safest way to check a CNAME record is to use the nslookup command. Go to the cmd (Command Prompt). Type “nslookup”, and press Enter. Now type “set type=cname”, and press Enter. The last pass is to write down the hostname, which you want to check. See this example, “mail.bing.com” and you will see the canonical name “star-bing-com.a-0001.a-msedge.net”.

If you are using Linux, go for the dig command. Open the Terminal and type “dig cname mail.bing.com,” and you will see the same “star-bing-com.a-0001.a-msedge.net” plus additional information. Dig command has very rich answers.

CNAME vs ALIAS

There is a newer type of DNS record called ALIAS that also points one hostname to another. It can do almost all that the CNAME can, but it can coexist with other records and can be added to the apex zone.

CNAME vs A record

The CNAME and the A records are very different. CNAME point one hostname to another while the A record points the domain name to an IP address. Also, if you want to resolve a domain, and first you get a CNAME, then you will need the A record too. So, the CNAME will take 2 queries instead of 1.

If you are interested in DNS records, check our article about the DNS CAA record!

Reverse DNS and PTR record – everything you need to know

Reverse DNS

Reverse DNS is a key component of the configuration of your mail server. 

Not having Reverse DNS can mean not sending emails! Without well-configured Reverse DNS zone and PTR records, the rest of the email servers can’t check your domain’s IP address and discard your messages or throw them into the spam box.

Everything you need to know about Reverse DNS

A Reverse DNS is a service that provides Reverse DNS zones for your domain. The Reverse DNS zones serve to host PTR records that can be used for verification purposes, to check the IP addresses and if they lead to the correct hostnames.

The mail servers of other companies that want to send you emails need to make sure that the IP address that they are seen truly belongs to your domain. Otherwise, they can send the emails to another place, and criminals might use the information.

It is used for different services, too, for the same purpose to verify that a particular IP address belongs to the domain name.

The Reverse DNS can be used to point IPv4 or IPv6 addresses to hostnames. You can add both PTR records with IPv4 and IPv6 addresses inside the same Reverse DNS zone.

Why does the Reverse DNS matter?

The Reverse DNS matters because without it, your emails might not arrive at their destination. The mail servers of the receivers will check your PTR records, among other DNS records, and if they don’t find them, they might not trust your domain and discard the emails you are sending them.

Everything you need to know about the PTR record

The PTR record is the DNS type of record that you use for Reverse DNS and links IP addresses (it can work both with IPv4 and IPv6 addresses) to the domain name. When the receiving mail servers whats to check the origin of an email, they will perform a DNS Reverse lookup, and they will search for PTR records. The PTR records will guarantee that the IP truly belongs to the domain name.

How to perform Reverse lookup and PTR lookup?

You can perform a Reverse lookup using the nslookup command. The nslookup command is available on all popular computer OSes.

For Windows users, use the Command Prompt, and for macOS or Linux users, go for the Terminal application. There you will need to type the following nslookup command:

nslookup -type=ptr 91.198.174.194

We will specify the type of DNS record that we want, and for the Reverse lookup, we need the PTR record.

We are using the IPv4 address 91.198.174.194, but you can change it with whatever you like, so you can verify your domain or somebody else domain.

The result will be the name of the host. We can compare if this name is related to the domain we were expecting.

Conclusion

Now you know that Reverse DNS is and how it uses PTR DNS records to point IP addresses to domain names. Start using them for your domain and reduce the bouncing rate of your sent emails. It is not hard. It is just a matter of knowledge.

DNS TXT record explained

DNS TXT record

There are a lot of DNS record types, at least 50 out there! One of them is called DNS TXT record, and it has a variety of purposes. Yes, it is one simple text record, but it is widely used, so let us explain the TXT record.

TXT record explained

TXT record is a DNS record type that has text information designed for external to the domain sources. The text could be written for people, so it would be easy to read, has enough information and logically organized, or made for computers, and has a more technical format.

Usually, you will see, inside the TXT record, a piece of general information about the domain and an additional part for a particular type of validation.

What’s inside a DNS TXT record?

There are just a few fields that you can manage:

  • Host: Hostname/ domain name, for which we are creating the TXT record.
  • Type: TXT – the DNS record type.
  • TTL: Time, that this record is cached on the recursive server.
  • Points to: Here, you can put a different value, depending on the purpose you decide.

Why do you need a TXT record?

The TXT DNS record has multiple purposes and can work with different software, including various email verification methods for incoming and outgoing email servers:

  • SPF – Sender Policy Framework is a method for authentication of emails, checking which of the servers has the right to send emails for a domain and has different mechanisms in case of wrong sender parameters.
  • DKIM – DomainKeys Identified Mail. It is a cryptographic authentication method for signing mails and proving that they are coming from a particular domain.
  • DMARC – Domain-based Message Authentication Reporting and Conformance is a security mechanism that proves who the sender of an email is and lowers the number of spam messages.
  • Verification for software – Big companies like Microsoft (Office 365), Google and more, need you to add a TXT record in your DNS zone to prove it is yours. It combines the SPF and DKIM authentication and works with them.

How to probe TXT records

We will use Wikipedia.org for checking their TXT records, but you can just replace it with your domain name and see your TXT records.

Check TXT record on Windows

Open the Command Prompt. Press “Windows key + R”, the Run application will start, and there you can type “cmd”, and press the Enter button. Inside the Command Prompt, we will use the nslookup command.

nslookup -type=txt wikipedia.org

Check TXT record on Linux and macOS

On Linux and macOS, there are many ways that you can check the TXT DNS record. All of them will involve using the Terminal application, so please start it. 

Dig command on Linux and macOS

Dig command is one of the most powerful tools for performing dns queries and debug your dns configuration, for example – what are your current TXT records. Here are some examples how to check the TXT record for a domain name:

dig wikipedia.org TXT

or you can use a specific one to check the DMARC record:

dig _dmarc.wikipedia.org TXT

Host command on Linux and macOS

host -t txt wikipedia.org

Conclusion:

After this article, you should know what the TXT DNS record is, why does TXT record exist, how to check the TXT record so we can easily say, TXT record explained! 

What is Time To Live (TTL)?

Time To Live TTL

What is TTL?

Time To Live (TTL) sounds like a horror movie, but luckily it is not related to people. It is the value that shows how long the information should be kept in a particular device. There are many pieces of data that have their own TTL value. Here we will see DNS TTL and CDN TTL. 

When we are talking about DNS TTL, it is related to the time that the DNS resolvers must keep the DNS records in their cache. Each of the DNS records will have its TTL value. There are some with longer TTL because there is less chance that the value will change and others with shorter TTL value, where there are often changes. 

You can use these values as an orientation for your DNS records:

  • A and AAAA records – 2 hours (7200 seconds) is ok.
  • CNAME records – up to 12 hours (43200 seconds)
  • MX records – keep it as low. 1 hour (3600 seconds) is ok. 
  • TXT records – up to 12 hours (43200 seconds).

And about the CDN TTL, there we are talking about caching the whole content and how long should the cache servers keep the photos, videos, or whatever needs to be cached. 

When the TTL expires, the servers need to discard the current data that they have and make a new query to get the updated information from the primary servers. 

How does TTL work with DNS queries?

Talking about DNS requests, they are packets of data that also have TTL value. Imagine if they didn’t have such a parameter! The first-ever DNS query could still be around, going from server to server. 

So the TTL value of a DNS request is there to stop the perpetual search or answer and reduce pointless stress on the system. 

The value starts with a bigger number and gets dropped when it comes to zero by the routers. 

How to check the TTL value on Windows?

If you are a Windows user, you can use the Nslookup command and check a particular DNS record like – SOA, A, MX, AAAA, and more. Change the type with the one you want to see.

Start the Command Prompt as an administrator, and use this:

nslookup –types=soa yourdomainhere.com

How to check TTL value on Linux or macOS?

You have more options on Linux and macOS. You can use different commands through the Terminal application. 

The Dig command can show you different DNS records, and you can see their TTL value. This example will be with A DNS record.

dig a yourdomainname.com

You can also use the Host command in a very similar way:

host –a yourdomainname.com

This command will show you all of the visible DNS records with their TTL values.

Conclusion

The TTL value is a necessary part that limits the time a data is valid. It will show if the data is current or if it needs to be updated soon. It makes data updates easier.

 

DNS propagation explained

DNS propagation

Imagine this situation. You have finally decided to truly manage your DNS. You have selected a DNS service provider, you have created master and secondary zones, and you have added all the DNS records that you will need. You spend a lot of time and effort. And after everything is ready, you want to check and… there are no changes! Don’t worry. The DNS propagation takes time.

What is DNS propagation? 

It is a process to update the changes that you make in your DNS. After editing or creating new DNS records, they are saved in the authoritative DNS nameserver. That is ok, but what about all the rest of the DNS name servers? The cache memory of the recursive DNS servers will still keep the older versions of the DNS records based on their TTL value.
The DNS propagation is the time it will take to propagate, to update the changes to all of the recursive name servers.

Frequently asked questions about DNS propagation

Do you have any doubts about the DNS propagation, we hope you can find your answer here:

Could we make the DNS propagation faster?

Of course, we can, but there is a catch. Boosting the speed depends on the TTL value of the DNS records, so lowering the TTL value of each of the DNS records will indeed guarantee faster DNS propagation. The problem is that you might not want to have DNS records with low value. It will stress more your DNS servers, updating them too often.
We don’t need all of our DNS records to update all the time.
It is better to keep the records’ TTL values at their normal level. Plus, editing all of them will take a lot of time.

Can you check if the DNS propagation is ready?

Of course, we can, and this time there is no problem. You need to see if the IP address for a domain name has changed. This will indicate that the A or AAAA records are updated already.
We will show you different ways depending on your OS.

*Change yourdomainname.com with your actual domain name.

Linux or macOS

Open the Terminal, and we will use one of the built-in commands called the Dig command.

dig yourdomainname.com

You can use the host command too, whatever you prefer.

Windows OS
The Terminal alternative in Windows is the Command Prompt. Inside it, we will use the NSlookup command.

nslookup yourdomainname.com

How long can the DNS propagation take?

It can take a long time. Depending on when the recursive DNS servers updated themselves and the TTL values of the DNS records, it can take as much as 72 hours.

Conclusion

Waiting for the DNS propagation to occur is a time-consuming process that we could not fully predict. This is the situation, and there is little we can do, so just be patient, and in less than 72 hours, the update will happen.
Patience is the key here!

CAA record explained 

CAA record explained

CAA record is a DNS record that shows who can be the Certification Authority for a particular domain and issue certificates.

What is Certificate Authority (CA)?

The CA is the entity that has the right to issue certificates like SSL certificates or TLS certificates. You can easily identify the CA, based on their name and their certificate revocation list (CRL). The Certificate Authority must provide a public key or a certificate from their CA if it is subordinate.

What is the CAA record?

The CAA record (Certification Authority Authorization) is a DNS record that a domain name owner can use to specify the certificate authority which can issue for their domain name. Inside the CAA, the domain owner can adjust the settings that cover the whole domain or just particular subdomains.

If you manage the CAA on a domain level, it will automatically apply on the subdomain level, too, unless you set it inside the record.

The CAA work with both wildcard certificates and single-name certificates. Separate and together too.

Why do you need to use DNS CAA record?

Continue reading

Anycast DNS vs Unicast DNS

Anycast DNS vs Unicast DNS

What DNS servers mainly translate domain names of websites into IP addresses. Servers communicate among them to identify data’s location of the domains we required to make them accessible. 

To know where your website is hosted, you definitely need a DNS server. Two popular DNS routing models are Unicast DNS and Anycast DNS.

What is Unicast DNS?

With Unicast, only one server stores the IP of the website. Its info is available where that DNS server is situated. No matter the place in the world, users request to visit the website, they have to get to this exact point.

DNS request will go to DNS name servers of users ISP, looking for an answer. If it doesn’t get an answer there, it will go from server to server, searching for one that can answer.

In the case of Unicast, we have just one that can answer. 

Suppose the server that has stored the website data is close to the requester, great! He will get a fast answer. But a user requesting the same website from far away will have to wait much more time to get the same answer from the same name server. 

Advantages of Unicast DNS

  • Unicast means one machine, one IP. So installing unicast is simpler because you have to be worried about the maintenance and proper performance of just one server.
  • Therefore, Unicast is cheaper than Anycast. There are different alternatives, but Unicast is still very used on the Internet for its price.
  • It is a choice for websites that target specific markets and not the whole world. If your business is directed just to Chinese users, you can choose Unicast, a DNS server in such a country, so your website will be easily reachable since it is close to your audience and your budget won’t be affected.

Disadvantages of Unicast DNS

  • If the DNS server that stores your website data gets attacked or crashes, accessibility to your website will be seriously affected.
  • If your business targets potentially people all around the world, Unicast DNS is not the best for you. As explained before, you can’t guarantee the best experience for users located far from your server’s location.

What is Anycast DNS?

Several servers located in different geographical points can provide the same IP through Anycast. DNS information from your domain name is copied on as many servers as you pay to have a better presence.

With Anycast, the closest DNS server will answer the user’s request. If one is down, offline due to maintenance or a different reason, the request will go to the second closest, available DNS server to get the answer, and so on. Then user’s request definitely will be answered faster, and the experience will be better in terms of waiting for a response, loading time, etc.

Advantages of Anycast DNS

  • Faster response time. The faster the servers’ response is, the shorter waiting time and fewer potential clients abandoning your site. 
  • Higher uptime and accessibility. A server can fail, but a whole group of servers rarely, at least not at the same time. Therefore, your site will have higher uptime, and access will be guaranteed for users at any time.
  • Better position on search engines. Positive user experience (short waiting response, fast loading, accessibility, etc.) is considered by search engines to rank better or worse your site.
  • Better security. If one server gets compromised, you will have others to rely on.

Disadvantage of Anycast DNS

  • Having more than one server is clearly more expensive. Depending on your budget, this could be a problem.
  • Configuring all servers takes a bit of extra effort but is worth it.

Conclusion

Anycast is clearly more robust than Unicast. What really defines which is more suitable, it’s your business size and needs.

Vanity name server (DNS branding) – Why use it?

Vanity name server (DNS branding)

Did you know that there is a DNS service that allows you to put your custom DNS branding on the name servers the DNS provider offers? With DNS branding, you can put the name of a domain you own instead of the names that come by default, like ns1.DNSprovider.com, and be changed to ns1.YourDomain.com.

Why would you want to use Vanity name server? 

What is a Vanity name server (DNS Branding)?

DNS Branding offers vanity name servers that are name servers that you can put a custom name on them instead of the DNS provider’s default name. You can put your own domain name, hide the DNS provider, and have a better brand image. 

See the following example of Vanity name servers, so you get the idea better:

BeforeAfter
ns1.DNSProvider.com ns1.YourDomain.com
ns2.DNSProvider.comns2.YourDomain.com

DNS Vanity name servers are actually a mask on top of the DNS provider.

Anycast DNS vs Unicast DNS

Why use Vanity name server?

Because using Vanity name server will show the custom name, like ns1.YourDomain.com, when somebody is performing a Whois lookup or using any of the commands for testing NS DNS records. 

Another reason is that using this DNS branding is that you can hide which exactly is your DNS provider or public DNS server you are using, so nobody uses this information against you in any way.

White-label services. You can offer different network services and make a deal with a DNS provider, to offer their services through your plans, without mentioning their involvement and slapping your brand on top of the DNS service. That way, you can add more features and look like a truly feature-rich service provider. 

How can you set up a Vanity name server?

Configuring Vanity name servers takes a few simple steps, and it is very similar on most of the DNS providers:

First, go to your domain registrar site and log in. There we need to add Child Name Servers to your domain. Those servers you want to use like ns1.YourDomain.com, ns2.YourDomain.com, etc., and add the IP addresses according to the domain registrar.

Now, go to your DNS settings and add the same A records as the Child Name Servers for the DNS zone. You can do it for your Primary DNS zone or Secondary DNS zone. Both work.

After adding the A DNS records, the same way as the Child Name Servers, it is time to change the NS records (name server record) that you can find the DNS zone. Edit the existing ones, or delete them and add a new one. The content of them should look like YourDomain.com NS ns1.YourDomain.com, and so on for the rest of them.

Time to get back to the domain registrar settings. There, from the control panel, change the previous name servers with those you just created. You might need to wait up to 48 hours to update the DNS records on all the DNS resolvers.

Now you know what Vanity name servers are, what purpose do they have, and how to start using them, are you interested in using them?

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