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CAA record explained

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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?

What’s inside the CAA DNS record?

You have several fields inside that needs to define each of the important values:

  • Type: CAA – the DNS type.
  • TTL: Time in hours – the TTL value for the DNS record.
  • Host: Hostname – for which the certificate is valid
  • Flag: 0/182 – Issuer critical value. 0 means not critical, and 128 means critical.
  • Type: issue/issuewild/iodef – issue means that the CA can issue any type of certificate; issuewild means wildcard certificate; iodef is incident description exchange format.
  • Value: The value that you receive from the CA you chose.

Why does CAA exist?

It is always good to have control. Having CAA defines who can issue certificates for your domains and limit abuse chances.

If you don’t have a CAA record, everybody can generate a certificate for your domain name and sign it with one of the CAs.

The CAA record and the CNAME record

In normal conditions, the CA will be searching directly for the CAA record for your domain. But what if we are talking about a subdomain and CNAME records pointing to the canonical name?

There is no problem. The CA will check if there is a CAA record for the subdomain, and if there is no such record, it will search for the CNAME record. If it finds it, it will check the CAA record for the domain, and it will issue a certificate for the subdomain too.

In case the CA does not find a CAA record, it can’t issue a certificate for the domain, and it won’t do it.

How to check a CAA record?

You can’t use the popular tools like nslookup, dig, or host commands. You will need to search for a “DNS CAA lookup” too online. There are many, so try to find a legit site for your DNS lookup. We tried https://gf.dev/, and it was successfully showing our CAA records.

Conclusion

Adding a CAA record is easy, will limit the chances for abuse, and won’t affect your DNS service’s performance, so it is better to have it.

List of the basic DNS record types

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Dо you want to learn more about the different records? If yes, you are in the right place. Here you can find the list of the most popular DNS record types.

1. SOA record

The Start Of Authority record, or SOA record for short, is the first on our list. It is the one that must be comprehended. Why? It represents the beginning of the Authoritative DNS zone. This DNS record contains a wealth of data for the DNS zone. If you want your network to run smoothly and without errors, you’ll need this DNS record. It sends all requests to the principal DNS server. In addition, the SOA record contains the information and contact information for the DNS administrator. A variety of parameters, such as the domain serial number, are also included. It’s worth noting that each DNS zone should have just one SOA record.

How many DNS record types are there?

2. А record

Any DNS list must include the A DNS record. It’s perhaps the most well-known record format. The A record is used to direct or point a hostname to its IP address. When talking about A record, the address is IPv4 (32-bit) (32-bit). A newer AAAA record type supports IPv6 addresses (128-bit) (128-bit).

As a result, your site’s A record will include the host (extranewspapers.co.uk), as well as the host’s location (89.32.146.196), type (A), and TTL (time to live). It’s the most often utilized DNS record.

3. PTR record

The PTR record is another crucial type, often known as a Pointer record. It is used for backchecks and performs the reverse of the A record. It connects a hostname to an IP address (IPv4 or IPv6). It’s required because the rest of the servers in the globe may request proof that an IP address corresponds to a hostname before accepting a service, communicating, or taking any other action. As a result, it is frequently utilized in the authentication of the host.

4. CNAME record

The CNAME record essentially displays the real domain name (canonical) for the domain or subdomain you’re looking for. This DNS record type is significant because it can be used for all your subdomains. They point to your domain name by adding a CNAME record for each of them. Additionally, you also don’t need to add any additional DNS records to your subdomains.

5. TXT record

We can’t omit the TXT (Abridged from text) DNS record. It is incredibly adaptable. It provides information to sources outside the domain in text format. The SPF record is a type of TXT record. It is used by mail servers to determine whether a message is trustworthy and from the correct domain.

TXT records could be used for various types of verification and authentication. For example, increasing trust in your domain and emails is critical for your online reputation.

6. CAA record

The DNS administrator of a domain uses the Certification Authority Authorization record, or CAA record, to add and establish which Certificate Authorities (CAs) can publish SSL or TLS certificates for the domain.

The domain owner benefits from the CAA record since it gives them control over issuing certificates. Furthermore, the number of incorrectly issued certificates for that domain will be minimized. You can utilize the CAA record for your entire domain or only part of the subdomains. It all relies on your particular preferences and the setup you choose.

Conclusion 

Let’s review. You are now familiar with one of the most popular DNS record types. They are as follows: SOA, A, PTR, CNAME, TXT, and CAA records. So, it’s now your turn to make them real in your Domain Name System. Good luck!

What does UDP mean?

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UDP explained

UDP stands for User Datagram Protocol, and it is a popular communications protocol that offers a high-speed solution. It is used for producing low-latency and loss tolerating connections between the different applications on the Internet.

User Datagram Protocol boosts the speed of the communication process by allowing the transfer of data before the receiver provides an agreement. For that reason, User Datagram Protocol is the preferred option for time-sensitive communications, such as Domain Name System (DNS) lookup, Voice over IP (VoIP), video or audio transmissions.

How does it work?

UDP divides each message into multiple packets named datagrams and transfers them over the different network devices, like routers, switches, security gateways, until they reach their target host or server.

For distinguishing the queries of the users, each datagram holds a header with precise port numbers. In addition, it provides a checksum choice, which serves for verifying that the data transfer is complete. That is essential because User Datagram Protocol splits the messages, yet it doesn’t put them back together, and it doesn’t number them.

The most attractive feature of User Datagram Protocol is exactly that it offers high-speed communication. That is due to the fact it is a connectionless protocol. It boosts the speed of the transfer, but packets can get lost, and there is a potential for a DDoS attack to occur.

Applications relying on UDP

UDP and DNS 

DNS (Domain Name System) implements a group of different protocols, and one of the essential ones is exactly the User Datagram Protocol. Here are some of the key reasons why DNS uses User Datagram Protocol:

  • Thanks to User Datagram Protocol, DNS optimizes its work by implementing it for sending small data packets. That is very beneficial for the process of DNS resolution. The DNS queries for DNS data (DNS records) are mostly small, and UDP is able to transfer them quickly. 
  • DNS provides quick answers because UDP allows the transfer of data without completing a handshake process. The Domain Name System values that!
  • User Datagram Protocol is able to support a large number of DNS users simultaneously, thanks to the absence of connection conditions. On the other side, for instance, TCP has Receive and Send buffers.

UDP vs. TCP

UDP and TCP are probably the most popular protocols out there. Both of them run on top of IP – UDP/IP and TCP/IP. Yet, they are very different.

  • UDP is connectionless, and TCP is a connection-oriented protocol.
  • TCP is considered a reliable protocol because it ensures the delivery of data packets. UDP does not guarantee the delivery of the packets.
  • TCP implements a three-way-handshake procedure. UDP does not wait for agreement.
  • UDP is way quicker than TCP. That is because it does not involve error checking, flow control, or guarantee. 
  • TCP includes a flow control mechanism that does not allow a lot of packets to be sent to the destination simultaneously. User Datagram Protocol does not follow such a mechanism.

4 great free DNS hosting providers

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DNS hosting service is a must to have for a domain to exist. No matter the size and type of domain you are planning to build (a big e-shop or a blog), you need this infrastructure for the domain to be accessible to visitors.

Choosing a quality provider is essential because DNS hosting impacts other important factors. A good or bad service will boost or hinder the domain’s performance, uptime, security, and speed. And, of course, the experience of users while visiting it. 

​Why get free DNS hosting?

When searching for a DNS hosting provider, you have the choice of paying for the service or getting it for free. Paid services include premium features and more possibilities. But currently, there are reliable and robust enough free services for hosting almost any type of domain. Some free DNS hosting providers offer you: Dynamic DNS, IPv4, and IPv6 support, one account multiple domains, support for a wide variety of DNS records, forward and reverse DNS zones support, customer support, etc.

​ClouDNS

ClouDNS provides both free and paid plans. Its free plan includes 4 Unicast DNS servers, 50 DNS records, 1 mail forward, web redirects, and 500 thousand DNS queries per month, a pretty good amount if you compare with competitors. It supports different DNS records types, not only the basics. Besides, you get Dynamic DNS that it’s a very convenient and time-saving solution. Clear statistics about DNS traffic and live-chat support with experts. A big advantage is whenever the free plan is not enough for you, there’s no need to migrate to another provider. You avoid the risks and complexity of a migration move by just scaling to a paid plan.

​Namecheap

Namecheap has another attractive free DNS plan that everybody can use. All third-party domain owners could try it. It supplies web redirects, Dynamic DNS, good support for different DNS records (ALIAS, CNAME, NS, ALIAS, etc.), 24/7 customer support. This provider offers you a convenient advantage. You can use a Secondary DNS to have a reliable backup and to get redundancy! This is not a feature to ignore. The higher uptime for your domain, the better! Namecheap also provides free and paid plans. There’s room for your domain to grow!

​Hurricane Electric Internet Services

Hurricane Electric Internet Services offers a free DNS hosting service. One highlight is strong connectivity due to a solid network integrated by more than 60 points of presence (PoPs) worldwide. Besides, it offers multiple domains per account, IPv4 and IPv6 support, different DNS records support (CNAME, CAA, dynamic TXT, ALIAS, HINFO, NAPTR, etc.), multiple reverse zone formats, and Dynamic DNS support. Furthermore, this provider is constantly adding to its service to support more technology and make your DNS domain’s possibilities wider. 

​GeoScaling

GeoScaling has nameservers in 3 countries, up to a million DNS requests monthly, support for most DNS records, Dynamic DNS support, the ability to upload and import BIND zone files. You can modify DNS records without reloading the page, low TTL (time-to-live) for faster propagation. A highlight is that this service can analyze the incoming traffic and redirect it considering the user’s location. This is a premium feature that not every free service offers.

​Conclusion

Free DNS hosting service can be your choice! There are quality providers you can rely on to exist and live the online adventure. Analyze what you want to build to understand its needs fully. Perhaps you can give it a chance and enjoy its benefits!

Tracert command explained

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If you are a Windows user and you want to trace the route from your computer to a specific target, the easiest option is to use the tracert command. With just a simple text command, you will see the hops.

What is the Tracert command?

The Tracert command is a Windows command with CLI that you can access through the Command Prompt, or if you prefer the PowerShell too, and use it to trace the route to a target. You will see statistics about each hop that show the response time (it sents 3 packets), IP addresses of the hops, and their hostnames.

The targets can be hostnames or IP addresses.

Use the tracert command to see how much time it takes to reach a target, through where exactly does the query goes if some of the hops take too much time to respond. Later, you can focus your attention on the spots that responded slowly and see if you can improve anything.

What makes the tracert great is that it is already on your computer, and it is very simple to use. After this article, you will learn how to use it for your needs.

How to use the Tracert command?

If you are using Windows 10, Windows 8, Windows 7, or even Windows Vista, you can use the tracert command through the Command Prompt or the PowerShell. Choose the one you like. You will get the same functionality.

You can use the following tracert syntax to see better how to for your queries:

tracert [-d] [-h maximum_hops] [-j host-list] [-w timeout] [-R] [-S srcaddr] [-4] [-6] target_name

You can use additional options to specify the tracert command. Add them after the “tracert” in the command, separated with a single space. After the option, leave one space and put the target (hostname or IP address).

See the examples below and try the tracert command yourself. In our examples, we are using Google.com, but you can change it to your domain or your site’s IP address and see the results.

Tracert command options and examples

Don’t show the hostnames.

tracert -d google.com

You will see each hop’s IP addresses and time for the response, but no names.

Change the maximum hops for the query.

tracert -h 45 google.com

You can set a number that you like. The default is 30, but if you want to check a very far away target, you can set it at 45, like in the example of tracert above.

Loose source route along host-list (IPv4-only)

tracert -j google.com

This command will show only IPv4 addresses. 

Set the maximum time for waiting for a response.

tracert -w 125 google.com

Roundtrip traceroute 

tracert -R google.com

In some cases, you would like to use the tracert command to check the route back, not only going forward. You want to see if there is any strange host, which was not there, in a normal query. 

Source addresses IPv6-only.

tracert -S google.com

Set only IPv4 addresses.

tracert -4 google.com

That way, you will see only the IPv4 addresses of the hosts through the route.

Set only IPv6 addresses.

tracert -6 google.com

That way, you will see only the IPv6 addresses of the hosts through the route.

Conclusion

The tracert command is a small software that you already have on your computer and can serve you to trace the route of a query to a target. The best part is that it is included in Windows by default, so it will always be there when you need it.

What is IPv4?

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The Internet is a massive kingdom. With the number of networks and the millions of devices that daily get connected, chaos could be the king ruling it. But an order is required to be efficient, and creators knew it. That’s why they developed protocols like the IP.

What is IP? 

Internet protocol (IP) is a group of communication rules for controlling the format of all the data sent through local networks or the Internet. 

The things that most people know about it are the IP addresses.

IP establishes the most convenient structures for packets to transport the data until they are delivered. It also involves different ways of addressing. And it routes datagrams across networks. The delivery of data packets from a source to its destination relies on IP addresses. 

The Internet has to know who is talking with. Who requests something and for who an answer is: servers, routers, websites, computers, smartphones, Internet of Things (IoT), etc. IP addresses help to identify and to make accessible machines, devices involved in a specific communication. That is how the exchange of data is possible.

What is IPv4?

Internet protocol version 4 (IPv4) is a widely used version of the IP. It is not the newest but still it is very popular. Through IPv4 addresses, identification of devices on networks is possible. Their structure is 4 numbers between 0 to 254, separated by dots, just like this one: 132.95.251.16. IPv4 uses a 32-bit address space. 

IPv4 is the result of the TCP/IP improvement. It was used for the first time in 1982 by SATNET, and in 1983, by ARPANET.

It is a connectionless protocol, meaning that messages can be sent without a previous arrangement between two endpoints on a network. One device sends data to another without checking if the recipient is available and with the conditions for receiving the data. 

IPv4 works on a best-effort delivery model. It is not part of its mission to guarantee the proper delivery. It is neither responsible for avoiding duplicate delivery, securing the order, nor protecting data integrity. It needs a teammate, another protocol to be in charge of such tasks, like the popular TCP (transmission control protocol).

Shortly, IPv4 only defines the format, communicates, addresses, and routes data.

This functionality makes it an essential resource for different interconnecting networks and for transmitting data from sources to their destinations. First, the data’s format is checked. If it’s too big, it is cut in parts for better transmission. Then these datagrams travel from an Internet module to another to reach the destination.

Advantages of IPv4.

  • IPv4 is four decades old. Time enough for improving it and guarantee systems support. Nowadays, it is not an issue for systems to handle this version. IPv6 means attractive upgrades but still has a long way to be as supported as IPv4.
  • IPv4’s prefixes are simple. This is convenient for networks’ topology, physical and logical. They fit easier.
  • IPv4 addresses are easier to type manually if needed. They are shorter than IPv6 ones—fewer possibilities of human mistakes.

Disadvantages of IPv4.

  • There are not many IPv4 addresses available anymore. There are millions of connected devices in the world, and each needs a unique IP address to connect successfully. Currently, we are already in the transition to the latest Internet protocol, version 6 (IPv6). 
  • IPv4 header is limited to 60 bytes. No more parameters can be added.
  • IPv4 is well supported by all systems. Many people prefer it. This increases the price of the available IPv4. 
  • IPv4 does not originally support Internet protocol security (IPsec). The protocol to authenticate and encrypt data packets for securing them. You can configure it, but it’s not an easy process.

Conclusion.

IPv4 is the past, and IPv6 is the future. Slowly we are going to start saying goodbye to the old one and welcome the new. 

What is Ping command, and how to use it?

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What is Ping command?

Ping command is a simple network utility tool. It has a command-line interface. You can write different commands and test various elements of your network – a computer on the network, the router, a particular domain, or IP address.
The ping command uses ICMP – Internet control message protocol. When you are performing a check, you need to set a target, and additionally, you can add options for the number of packets, continuous pinging, timeout limits, IPv4 or IPv6, and more.
You will get a response with additional statistics.
An ICMP request is a small packet of data that your computer will send to the target. The target should bounce it back and send an answer for each ping.
You can find the Ping command on Linux and macOS through the Terminal application, or on Windows, through the Command Prompt.
You should also be able to find it on Android or iOS/iPadOS through a third-party Terminal application. 

Ping command – examples, switches, and more!

How to use Ping command?

Let’s see first how to use ping command on Linux or macOS and check a few examples.
Open the Terminal application.
For some of the cases, you can use Windows too. On it, you will need to open the Command Prompt for performing the commands.
*We will use example IP addresses and yourdomain.com. Please feel free to change the text and use the examples with your own domain or device (IP address).

Basic Ping command. You will see if you can reach the target. That way, you can see if you, or the device you are probing, are connected. The result would be continuous ping on Linux or macOS (Stop with Ctrl-C), or 4 replies and statistics if there were no problems.

ping yourdomain.com

For continuous ping on Windows, you need to use the extra option “-t” and the ping that you want to perform is:

ping -t yourdomain.com

Send more ping requests (custom number of requests). You can make more than 4 requests on Windows or a specific amount of requests on Linux/macOS.

Linux/macOS
ping –c 8 yourdomain.com

Windows
ping –n 8 yourdomain.com

Set an interval between the pings. You can set the time in seconds between the requests.

Linux/macOS
ping -i 20 8.8.4.4

Set a timeout period in seconds to stop the ping command on Linux/macOS.
ping –w 50 yourdomain.com

Get the statistics only on your ping request, not showing the individual pings.
Linux/macOS
ping –q yourdomain.com

Set the packet’s size to a value that you want. The default is 56 bytes on Linux/macOS and 32 bytes on Windows. Let’s put 112.
Linux/macOS
ping -s 112 yourdomain.com 

Ping option for extended functionality Linux/macOS and Windows.

For those of you who are using Linux or macOS, in the Terminal application, write:
ping -h

-aYou will hear a sound when the pings arrive.
-bAllows the ping to broadcast IP address.
-BDon’t allow ping to change the source IP address.
-c (count)The number of ping to send.
-fFlood the network with pings.
-i (interval)Interval between pings.
-I (interface address) Source IP address to interface IP address.
-1 (reload)Number of pings without waiting for replies.
-nShow hostname in result.
-qShort answer.
-T (ttl)TTL.
-vVerbose output.
-VVersion of ping command.
-w (deadline)Time to stop the ping command.
-W (timeout)Waiting time for a resonse. 

For Windows users open the Command Prompt and write:

ping -?

-tContinuos ping.
-aResolve IP address to hostname.
-nNumber of pings.
-lSend the size of the buffer.
-fStop IPv4 flag fragmentation. 
-iTTL.
-vNot working anymore.
-rTrace route IPv4.
-sTimstamp on each hop IPv4
-jLoose source route along host-list IPv4.
-kStrict source route along host-list IPv4.
-wWait for response time.
-RTrace route IPv6
-SSource address.
-cRouter compartment identifier.
-pPing Hyper-V network.
-4IPv4.
-6IPv6.

CNAME record explained

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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.

What is the difference between DNAME record and CNAME record?

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

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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.

Why do you need PTR records?

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.

What is TCP?

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Transmission Control Protocol (TCP) is a communication standard, one of the first internet protocols (TCP/IP). It is connection-oriented, for all kind of devices and applications to exchange messages through a particular network. 

Data is organized in a specific way by TCP to be transmitted between client and server. The purpose is to protect the data on their trip around the network from the sending to the delivery.

TCP is a very popular protocol in network communications. 

How does it work?

Transmission Control Protocol (TCP) was created for sending packets on the Internet, making sure the proper data and messages’ are delivered through networks. It works through a process that involves different steps. 

As mentioned previously, TCP is connection-oriented. This means it has to make sure the connection between source and destination is not only set, but also kept until the whole exchange of data (sending and receiving of messages) is completed.

Thus, the first step is TCP sets the connection needed by a source and its destination. During this period, there’s a connection, but there’s not data transmission yet. 

Then communication starts. TCP gets messages from the sender (server or application) and split them up into packets. TCP organizes the chopped data with numbers to have control over all the packets and protect messages’ integrity. 

Already chopped and numbered, messages will go to the IP layer for transporting. They will be sent and re-sent by the different devices involved in the network (gateways, routers, etc.) until they reach their destination. All packets belonging to a message have the same destination. But they all can travel following a different route. 

As soon as they arrive, they are rebuilding. Yes, through the numbers assigned to every message’s packet, it puts all packets together again. 

Once messages are built, they are delivered to their recipient. 

You know that network congestion, traffic load balancing maneuvers, and other factors can affect networks’ performance. TCP can solve those problems if such causes affect packets and get duplicated, disordered, delivered, or lost. The protocol can identify the specific issue, then request the lost data to be transmitted again, and reorganize in the proper order, disordered packets.

If, after fixing problems, messages still don’t get delivered, the source is informed about the failure.

Without a doubt, Transmission Control Protocol (TCP) is a reliable standard and a key for the Internet to work better and more precisely. 

There are different protocols, but if you need accuracy and you can’t afford the loss of data (packets), TCP is ideal for you. That is why it is widely used by very well-known Internet applications like SSH (secure shell), FTP (file transfer protocol) or IMAP (message access protocol), SMTP (simple mail transfer protocol), HTTP (hypertext transfer protocol).

Advantages of TCP

  • It guarantees accurate end-to-end data delivery. The bytes received will be the exact ones (same order) originally sent. 
  • Its functionality includes not only issues’ detection (duplicated, lost packets, etc.), but also the ability to fix them.
  • It operates with network congestion avoidance, an algorithm that includes different mechanisms to control congestion problems (AIMD, congestion window, slow start…).

Disadvantages of TCP

  • It is focused on accurate delivery, and that takes time. TCP’s process and additional fixing of problems, in case they occur, can cause delays. We talk about seconds or milliseconds, but in the context of a demanding world (Internet), that can mean much.
  • It’s not a choice for real-time applications like voice-over IP or streaming media. The reason is TCP’s process doesn’t have a fast transmission as a goal.

Conclusion

TCP is a reliable tool, very popular on networks. If it is about accuracy for delivering data, no doubt TCP is the choice. 

DNS TXT record explained

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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.

How to start managing TXT records for your domain name?

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! 

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