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* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
The Domain Name Systems (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to [IP addresses](https://www.cloudflare.com/learning/dns/glossary/what-is-my-ip-address/) so browsers can load Internet resources.\
| `DNS Root Server` | The root servers of the DNS are responsible for the top-level domains (`TLD`). As the last instance, they are only requested if the name server does not respond. Thus, a root server is a central interface between users and content on the Internet, as it links domain and IP address. The [Internet Corporation for Assigned Names and Numbers](https://www.icann.org/) (`ICANN`) coordinates the work of the root name servers. There are `13` such root servers around the globe. |
| `Authoritative Nameserver` | Authoritative name servers hold authority for a particular zone. They only answer queries from their area of responsibility, and their information is binding. If an authoritative name server cannot answer a client's query, the root name server takes over at that point. |
| `Non-authoritative Nameserver` | Non-authoritative name servers are not responsible for a particular DNS zone. Instead, they collect information on specific DNS zones themselves, which is done using recursive or iterative DNS querying. |
| `Caching DNS Server` | Caching DNS servers cache information from other name servers for a specified period. The authoritative name server determines the duration of this storage. |
| `Forwarding Server` | Forwarding servers perform only one function: they forward DNS queries to another DNS server. |
| `Resolver` | Resolvers are not authoritative DNS servers but perform name resolution locally in the computer or router. |
If that does not work you can use fingerprinting techniques to determine the remote server's version -- the [`fpdns`](https://github.com/kirei/fpdns) tool is one option for that, but there are others.
You can grab the banner also with a **nmap** script:
fierce --domain <DOMAIN> --dns-servers <DNS_IP>#Will try toperform a zone transfer against every authoritative name server and if this doesn'twork, will launch a dictionary attack
If you are able to find subdomains resolving to internal IP-addresses, you should try to perform a reverse dns BF to the NSs of the domain asking for that IP range.
You can query reverse IP ranges to [https://bgp.he.net/net/205.166.76.0/24#\_dns](https://bgp.he.net/net/205.166.76.0/24#\_dns) (this tool is also helpful with BGP).
If **DNS recursion is enabled**, an attacker could **spoof** the **origin** on the UDP packet in order to make the **DNS send the response to the victim server**. An attacker could abuse **ANY** or **DNSSEC** record types as they use to have the bigger responses.\
The way to **check** if a DNS supports **recursion** is to query a domain name and **check** if the **flag "ra"** (_recursion available_) is in the response:
Simply sending an email message to a nonexistent address at a target domain often reveals useful internal network information through a _nondelivery notification_ (NDN).
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
