Network

DNS Network

What is TTL and why is it important?

In our article today, we will take a look at the TTL. So, if you want to learn more about its purpose and why it is so important, you are in the right place. 

TTL – What is its main purpose? 

The value that specifies the time period or the number of hops that a data packet is put up to be alive is called time-to-live (TTL). Either across the network or in cache memory. It will be terminated when this timer runs out or the data packet hits its hop limit. Data packets are not all the same; they differ in size and shape, but they all have a unique TTL. The amount of time data packets should decide the time needed to live in a device to perform their missions.

How does it operate?

Massive volumes of packets will be routed around routers if they are not regulated. To get around this, each data packet must have an expiration date or a restriction. This makes it easier to track their progress and figure out how long they’ve been there. Packets also move through network points to get to their destination. As a result, a TTL value is included in each data packet. Only if time or hops are available, do routers receive the packet and forward it to the next network point. If the TTL indicates that no more hops/time is available, routers will stop transferring it.

On the other hand, routers send an ICMP (Internet Control Message Protocol) message. It reports IP errors and points to the packet’s source IP address.

Why is TTL important?

TTL is a critical method for controlling existing data packets and network traffic. Every day, networks get larger and larger. As a result, the volume of data packets passing through them is enormous. Without a means to govern them (expiration date), millions of old packets that served their purpose many years ago may still be floating around, causing confusion.

Time-to-live is an essential tool for determining if data is still valid in situations such as networking and device cache memory, as we previously discussed. Data that has been determined to be no longer useful can be discarded.

TTL also allows you to obtain information about packets, such as the amount of time they spent traveling and the whole route they took. This is critical information in terms of security!

TTL in DNS

TTL (time-to-live) in DNS (Domain Name System) indicates how long a DNS record, such as an A record or an ALIAS record, is valid (in seconds) and how long a nameserver (recursive or secondary DNS server) can store it in its cache memory. The DNS record will be removed when the TTL reaches 0.

The DNS client must ask the recursive DNS server again and wait for it to perform a fresh DNS query to obtain the record in the case of a recursive DNS server. Following that, it will be cached again based on the TTL.

To update its DNS records, a secondary DNS server must check with the primary DNS server again and complete a zone transfer. Otherwise, it will be unable to answer to domain-related questions.

Conclusion

To summarize, the TTL value is a critical component that determines how long data is valid. It will indicate whether the information is current or needs to be updated soon. It facilitates data updating.

DNS DNS records Network

PTR record: Why should you care about it?

PTR record is one of the critical DNS record types that you should know. It is one of the few that warrants special attention. Why, we will see in this article. 

DNS record – what does it mean?

To start, let’s see what precisely the DNS records are. They are nothing more than text instructions. Its primary function is to instruct domain name servers on managing traffic to your domains and subdomains. In addition, the network for websites is the entire Internet. So, a DNS record is a single mapping that connects an IP address to a resource in DNS. They are organized into DNS zones and kept on nameservers.

What is a PTR record?

PTR records, also known as Pointer records, are a DNS record that links an IP address to a domain name. It is proof that the IP address being checked is indeed tied to the domain name and that it is not a hoax. So, it allows you to check and verify that the IP address you’re using belongs to the domain name. Furthermore, it demonstrates that it is not a hoax. Thanks to the Pointer record, verifying distinct pieces or services, such as a mail server, is simple.

Structure

The structure of the PTR record is simple and easy to understand. Here is an example how what it could look like:

  • TYPE: PTR record – It denotes the DNS record type. 
  • Host: 78.159.213.32 – You must provide the host’s IP address in this field. An IPV4 or IPv6 address is possible.
  • POINTS TO: example.com – You can use this field to show the domain name.
  • TTL: 1h – You set the TTL or time-to-live value here.

How to create a PTR record?

It’s simple to set up a DNS Pointer record. So, let’s break it down into steps.

  1. It would be best if you first built a Master Reverse Zone.

In a Master Reverse Zone, the PTR record can exist. However, it’s important to note that it shouldn’t be used in a conventional Master zone. The IP address in the Master Reverse Zone should always be in reverse order. For example, if the IP address is 32.213.159.78., you should enter it as 78.159.213.32. Regardless of whether it’s an IPv4 or IPv6 address, the same rule applies.

  1. The next step is to generate the Pointer record.

When adding the PTR record, you’ll also have to input it backward. You should have a matching A or AAAA record for each Pointer record. As a result, make sure to double-check!

  1. Finally, add the NS records.

NS records pointing to your nameservers should be added to the IP provider. Your Reverse DNS zone is now complete!

Why is it important to use rDNS service?

PTR record vs. A record

When we compare the A and PTR records, we’ll see that they’re polar opposites. This is because the A record links a domain name to an IP address (IPv4). On the other hand, the PTR record is used to resolve an IP address (IPv4 or IPv6) to a domain name.

It’s also worth noting that the A and PTR records are located in separate DNS zones. The A record should be added to a Primary (Master) DNS zone, but the PTR record can only exist in a Master Reverse DNS zone and operate.

Conclusion

By and large, the PTR is a really fundamental DNS record that you have to know. Start using it for your domain to lessen the number of bounce emails. It is not difficult. You could just follow the steps above. Good luck!

DNS Network

The Ultimate Guide to DNS Propagation

What does DNS propagation mean?

DNS propagation is a process that includes updating and spreading the new changes and adjustments you create in your Domain Name System (DNS). They have to be distributed across the entire network. 

Managing your online business or administrating a network involves constant changes on the DNS. Some of the possible scenarios are when you have to add a new DNS record, delete or change some other DNS records, also replace IP addresses. Maybe you desire to make some adjustments on the TTL (time-to-live) values, redirect your visitors to a specific subdomain, or add an SSL certificate. These are only for illustration of how many different modifications of your DNS could appear. 

Actually, no matter what changes you desire to make, all of them are going to be stored on your authoritative DNS server. However, the network has many more DNS servers, like recursive DNS servers, positioned in different locations globally. Each one of these servers has to receive the updated data because if that doesn’t happen, they are going to have some difficulties operating properly. All of those DNS servers have a fundamental part of the DNS resolution process.

How does the DNS propagation work?

For several situations, DNS changes are required. Typical cases are when you desire to make some renovation to your website or when you migrate to a new DNS hosting provider. Different circumstances that can need it are redirecting from the primary domain to subdomains or implementing services, such as FTP and email. All of these circumstances incorporate activities, such as creating, editing, or removing DNS records

The administrator is going to make these corrections directly on the authoritative DNS server. Once the modifications are ready and saved inside it, it is time for the DNS propagation process to happen. That requires every DNS server on the network to obtain a copy with the latest DNS records. 

The DNS propagation process is rolling, although that doesn’t mean that it occurs simultaneously for all servers. 

How to check it?

Here you have three options to make a check on the DNS propagation. Decide depending on your operating system (OS).

For Linux and macOS users, here you have the Dig command.

First, open your Terminal, and next write: 

dig domainname.com 

It will trigger a lookup for an A or AAAA record. As a result, you are going to view the IP addresses of your website. If they have changed, DNS propagation is completed. If they haven’t, it will require a little more time.

*Replace with your domain name and TLD instead of the ones in the example.

For Windows 10 users, here you have the Nslookup command.

Open the Command Prompt, and then type: 

nslookup domainname.com

Once again, the lookup result is going to show out if your website’s IP addresses have changed or not.

*Replace with your domain name and TLD instead of the ones in the example.

Online checkers of DNS propagation.

You could use online tools for making DNS lookups to review data associated with your domain name. In addition, you can examine if the DNS modifications you created have been updated. 

Network

3 types of Load Balancing

Load balancing is a method of traffic management that will redirect the incoming traffic to your multiple servers. That way, non of them will get all the traffic, they will be able to manage less traffic better, and your network will be stronger. Now we will look 3 types of Load Balancing and how do they differ from one another.

Network load balancing

The network load balancing is ideal for balancing TCP and UDP traffic from clients over the internet. It operates on Layer 4 (the transport layer) of the OSI model (Open Systems Interconnection Model). When the network load balancer receives the traffic, it uses its algorithm and directs the traffic to one of the predefined servers in its list. It opens a TCP connection on the designated port and forwards the requests without modifying them. Not modifying them, but also not inspecting them, which means that the traffic is not checked about malicious packets, not it is organized based on the type of traffic it is. The focus here is just to transfer the traffic to various servers that are on the network.

You can use it when you are expecting large TCP or UDP traffic spikes, and you want to keep the packets unchanged.

It is easy to set up, scalable and it can save you during times of extreme traffic.

Classic

The Classic load balancing is very similar to network load balancing. It also can manage TCP and UDP, but also SSL, HTTP, and HTTPS traffic. The big difference here is that it works both on Layer 4 and Layer 7 of the OSI model. It has 3 components: the Classic load balancing instances, Listeners, and the Back-end servers.

The CLB instances will capture the traffic and distribute it to the Backed servers.

The Listeners will check the Back-end servers and see if they are functional. If any of them is down, they will give instruction to the CLB not to direct traffic to them until they are back in order.

The Classic load balancing is relatively economical, easy to set up, and provides good availability.

It also supports sticky sessions, so if a client connects to a particular Back-end server, it will stick to it and won’t go and connect to another for the time of the session.

Application load balancing

The Application load balancing works only on layer 7 (the application layer) of the OSI model. Here the load balancer is more intelligent and uses many parameters like hostname, host location (IP address), port number, and other parameters of the query. It supports protocols like HTTP, HTTPS, and WebSockets. It supports a sticky session that keeps the session open and doesn’t redirect to another instance. The Application load balancer checks the Back-end servers for different parameters and can take more advanced decisions regarding traffic distribution. It has the same components as the Classic one: load balancers, listeners, and back-end servers.

These are the 3 types of Load Balancing. You should pay attention to the protocols they use and at what level of the OSI model they work to properly understand them.