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Year: 2021

Oliver

How does the Host command work?

Commands

Host command explained

The Host command is a built-in utility software with a command-line interface (CLI) for DNS probing. You could find it pre-installed on most Linux distros like – Ubuntu, Linux Mint, Red Hat, or macOS. It serves perfectly for network diagnostics. In addition, the most common use of host command is to complete DNS lookups and check different information about a domain name and its DNS records.

 It is a very light and quick tool that can give you data about different DNS records, such as A, AAAA, MX, NS, SOA, and more. In addition, it can provide you with information for the host, for instance, its IP addresses or check nameservers.

Valuable Linux Host command examples

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Oliver

Ping command – definition and details

Commands

Ping command

Ping command is one of the built-in network diagnostic commands that you have inside your OS (Windows, Linux, macOS, FreeBSD, etc.). Ping is used for checking the connectivity between your device and the target that cloud be a hostname like google.com or IP address like 192.168.2.1.

Ping, by default, will send 4, 32-byte packets to the target using the ICMP (Internet control message protocol).

How does Ping command work? Detailed explanation

Default result of a Ping command

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Oliver

What is a DNS amplification attack?

DDoS attacks

What a scary combination! Just by reading “attack”, you can feel goosebumps. Then, when “amplification” is added, you can visualize an attack whose power could be increased to damage even more.

What is a DNS amplification attack?

The DNS amplification attack is the type of DDoS attack where a hacker spoofs its IP address and changes it to the target’s IP address, then performs a DNS query access to open, public recursive DNS servers to saturate the target (system) with DNS response traffic. The amplification comes from the answer, which may be many times bigger than the original request. 

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Oliver

How does the DMARC record work?

DNS, DNS Records

The DMARC record explained.

The short acronym DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. It is a mechanism, which provides the email receivers and senders to define if a particular message is legitimately from the sender. And also, what action to follows if it isn’t. The DMARC record helps recognize more easily phishing, and spam messages received in the users’ mailbox. It also assists in keeping these emails away from there. 

Example of DMARC

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Oliver

DNS troubleshooting – commands

Commands, DNS

You can troubleshoot different DNS problems using the built-in commands that you already have on your computer. No matter if you are a Windows, Linux, or macOS user, you have various commands included in your OS. Here are the 5 most popular DNS troubleshooting commands that you should know and how to use them.

Traceroute (Linux and macOS) / Tracert command (Windows)

Traceroute command on Linux and macOS or Tracert on Windows is a built-in software that you can use for DNS troubleshooting. With this one, you can understand better the route of the DNS queries. You will see each individual hop with their response time, hostname, and IP address, and you will see a complete picture of the route to the target.

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Oliver

What is DNS zone transfer?

DNS

The DNS is a hierarchy structure that looks like a tree. It is divided into layers where the top is the Root than the TLD-level, followed by the domain and the subdomain. You can get the right to manage a particular part of the DNS that is related to the domain you have purchase. You can manage it through DNS master zones that you can create from the software you are using or through the control panel of your managed DNS provider. 

What is a DNS master zone? 

The DNS master zone file is a DNS database of DNS records for a part of the namespace. A zone file typically will have SOA record, NS records, AAAA, A, MX, TXT, and other DNS records for the domain or subdomain. The master zone will be saved on a master DNS server (also known as the Primary DNS server). 

What is it?

The DNS zone transfer is the process of copying the information from the Master DNS server to the Secondary server or servers. The copying can be done by pushing the update from the Master DNS server to the Secondary servers or by a pull from the Secondaries to obtain the new changes.

The DNS administrator can limit which Secondary DNS server can ask for DNS zone transfer by whitelisting their IP addresses. You don’t want everybody on the Internet to be able to get all of your DNS records because many might be internals and not for everyone’s eyes.

Transferring a DNS zone using Dig

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Oliver

Authoritative DNS server vs Recursive DNS server

DNS

DNS infrastructure really makes Internet surfing an easy and pleasant experience. Have you ever thought about how connectivity for too many humans around the world is possible? DNS process is complex, and it repeats millions of times every day. Would you like to know some of the responsible actors for this scene to work efficiently? Let’s start with servers. Authoritative and recursive servers.

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