Tag Archives: DNS records

Is DNS cache important?

What is DNS cache?

The DNS cache is a temporary cache memory for storing DNS records of previously queried domain names. A lot of devices hold such memory mechanisms, such as DNS recursive servers, computers, tablets, mobiles, etc.

The idea behind it is for easy and fast DNS lookup, which is not necessary to repeat every time a particular domain name is requested. Let’s take, for example, the news website you visit every morning. The first time you requested to visit it, a DNS lookup was performed for the corresponding IP address. After the DNS recursive server stored its IP address, you were able to explore the website. Additionally, the DNS records were kept in the DNS cache. The next day when you open and search for the same website, the DNS resolver receives the available IP address from its DNS cache. Thus, it was not necessary for a new DNS lookup to be performed.

It is important to note that all the DNS records associated with the various domain names are going to be available in the DNS cache temporarily. Exactly how long time it is going to depend on the TTL (time-to-live) value, which the administrator sets.

The DNS queries of the users are able to receive a quicker answer and, also this mechanism helps with the efficient optimizations of the resources. 

How does it work?

It is a really helpful and important mechanism that saves a lot of time and Internet bandwidth. Let’s explain a little bit more about it and how it happens while following one DNS query. Every time when a user wants to visit and explore a domain name, it is essential to know the A or AAAA records for it.

  1. The first place to check it is the device’s own DNS cache. On every computer is stored a file that saves earlier visited domain names for a specific amount of time (TTL). Thus, the website will load without any DNS query to a DNS resolver if the data is still available there.
  2. In case the data is not available in the device’s cache, a query is performed to a DNS resolver, such as the one in your Internet service provider (ISP). If it is still stored there, it will answer the request, and the user will connect with the website without any further steps. If this is not the case, then a search through the root server, the TLD server, and lastly, the domain’s authoritative server is going to be performed.
  3. Once the required DNS records are found, they will be kept inside the DNS cache of the user’s device and the DNS resolver too. That is good news because next time the website is going to be faster and easier to visit.

The DNS resolver of an ISP will store DNS records of every explored domain name of each of their customers that requested it for an answer. For that reason, the chance is better to hold the answer in the cache memory for the next time someone requests a domain.

Why is DNS cache important? 

As we mentioned, the DNS cache is an effective mechanism for producing a faster and efficient DNS resolution process. It saves time, effort, and sources both for the network and the user’s device. The use of it is very appreciated for its characteristics.

5 most commonly used DNS records

DNS records are an essential part of managing a DNS. Every one of them has a specific and very important functionality. To achieve a perfectly working DNS, it is crucial to know what is their main purpose. Here we have 5 most commonly used DNS records that are good to know for a start. Let’s see which are they and what they do! 

SOA record

SOA for short means Start Of Authority, and it is important to know this record first. It indicates the beginning of the authority DNS zone. Inside it, you can discover information, which is crucial for the DNS zone. For the normal functionality of your DNS network, this record is a must-have. The SOA record indicates the primary DNS server. It includes data about the domain administrator and their email for contact. Also, parameters including the domain serial number and how often it should refresh. There should be only one SOA record for one DNS zone.

A record

The A record is probably the first one that comes to your mind when we are talking about DNS. Its purpose is very simple but yet essential. The A record connects the domain name (hostname) to its corresponding IP address. Every time a user wants to visit your website, will write the domain name, but what it actually needs to find is its IP address. The user’s browser will perform a search for the A record to resolve the query. Once it finds it, the browser will know exactly where the site is, and it will be able to load it to the user.

NS record

The NS (Name server) record is indicating precisely which are the authoritative name servers for a specific DNS zone. The NS record links your domain name to the hostname of the name servers. 

For example, yourdomain.net to ns1.yourdomain.net.

You need to specify which are the authoritative name servers and use the NS record. If you don’t do that, simply your DNS zone won’t work. That is the reason why we couldn’t skip this record in our list. It is crucial!

PTR record

This DNS record is also one of the must-haves in case you want to be able to send emails without problems. The PTR record has the exact opposite functionality of the A record. Also, this record is at the foundation of Reverse DNS. The PTR record points an IP address (IPv4 or IPv6) to a domain name. The need for this record appears when you send an email. The recipient requires to verify if this email was sent on behalf of the actual domain. You have to be careful when you configure your A record and PTR record because otherwise, your emails will end in the spam folder of your recipients. Nobody wants this to happen, right?

MX record

The MX record or Mail Exchanger record indicates the email server responsible for receiving emails for the exact domain. In addition, it points the domain name to the hostname of the incoming mail server. It is important to note that it is a hostname and not an IP address. You can add several MX records to create a backup if there is any difficulty. 

The reason to consider MX records is simple. Without it, you will not receive emails. For businesses, that is a pretty solid reason to care.