DNS Systems and Query Types

A hierarchical database system that translates hostnames to IP addresses.

DNS servers operate in a hierarchical structure with three major levels: root servers, top-level domain servers, and authoritative servers. Root servers provide the starting point for resolving a hostname, while top-level domain servers handle domains like .com, .org, etc. Authoritative servers are responsible for specific domains like google.com or example.com.

DNS uses specific query types to retrieve different information from the database. The most common is the A record (Address) which maps a hostname to an IPv4 address. Other types include MX (Mail Exchange), CNAME (Canonical name), and TXT (Text), each providing different domain details.

DNS servers cache recently used information to speed up subsequent lookups. This caching mechanism reduces the number of requests to upstream servers, improving efficiency and reducing response times.

DNS uses a standardized message format to communicate between servers. This format defines various sections like header, question, answer, authority, and additional information.

It occurs when an attacker manipulates DNS responses to mislead users or intercept traffic. This attack exploits vulnerabilities in the DNS system's trust model and can disrupt services or redirect users to malicious websites.

Implementing DNSSEC (Domain Name System Security Extensions) is a key step in protecting DNS from cache poisoning. DNSSEC uses digital signatures to authenticate responses, ensuring their origin and integrity.

DNS plays a crucial role in internet communication by resolving human-readable names into machine-readable IP addresses. It enables users to access websites, email servers, and other online services without needing to know complex IP addresses.

A function call used on UNIX-based machines to translate a hostname to an IP address.

A single, centralized DNS server that would store all hostname-to-IP address mappings.

A type of DNS server responsible for providing the IP addresses of Top-Level Domain (TLD) servers.

A type of DNS Server that stores authoritative records for a specific domain.

DNS servers that provide the IP addresses for authoritative DNS servers for various top-level domains (com, org, net, edu, etc.) and country top-level domains (uk, fr, ca, etc.).

A DNS server provided by an ISP that acts as a proxy, forwarding DNS queries to the appropriate servers in the hierarchy.

A DNS query where the local DNS server will attempt to find the requested information recursively, querying multiple servers if necessary.

A DNS query where the requesting server will only ask the contacted server and won't continue searching if the information is not found.

A way for DNS servers to speed up query resolution by storing recently used hostname-to-IP address mappings in memory.

A four-tuple record that represents a single entry in the DNS database.

A type of resource record (RR) that maps a hostname to its IP address.

A type of resource record (RR) that specifies the hostname of an authoritative DNS server for a domain.

A type of resource record (RR) that defines an alias hostname for a canonical hostname.

A type of resource record (RR) that maps an alias hostname to a mail server.

A program that allows sending DNS queries to any DNS server, often used for troubleshooting or checking DNS settings for a particular hostname or domain.

A type of attack where an attacker sends crafted responses to a DNS server, hoping to trick it into storing fake data about a domain. This can redirect users to malicious websites.

An attack where an attacker sends a flood of requests to a DNS server, overwhelming it and making it unavailable to legitimate users.

A type of malware that modifies the DNS settings on a computer, directing traffic to malicious websites instead of the intended destinations.

A method of verifying the authenticity of DNS responses, preventing attackers from injecting fake information into the DNS system.

A security measure where DNS servers check if the domain name in a response is the same as the one requested in the query. This helps prevent attackers from injecting fake information.

A technique where attackers target the DNS root servers, which are at the top of the DNS hierarchy, to disrupt DNS resolution for everyone.

A type of DNS attack where an attacker sends requests to a DNS server for a non-existent hostname, then sends fake responses containing malicious information.

A method of protecting against DNS cache poisoning by using a different port for each outgoing DNS query.

A malicious user sending forged DNS queries using the victim's DNS server, hoping to get it to send a spoofed response to a specific target.

Attackers sending a huge number of DNS requests to a target DNS server, causing it to become overloaded and unable to respond to legitimate requests.

A file that specifies the order in which the system searches for host mappings, prioritizing either the local /etc/hosts file or the DNS server. It typically sets 'order hosts, bind' for a prioritized search of the local hosts file followed by DNS.

The service responsible for managing network settings on a system. It can be restarted to refresh network configurations. It can be started/stopped/restarted with the command "/etc/init.d/network {start|stop|restart}"

The highest tier of DNS servers. There are 13 root servers in total, and they are the starting point for any DNS query. They delegate queries to the top-level domain servers for the appropriate domain.

A file that contains hints about root servers and their corresponding IP addresses. This file is used by BIND, the DNS software, to locate root servers when resolving domain names. The path to the file is typically /etc/bind/named.conf.default-zones

Generic Top-Level Domains (gTLDs) are the primary domains for a wide range of organizations, such as .com, .net, .org, .edu. Country Code Top-Level Domains (ccTLDs) are specific to countries, such as .uk, .jp, .fr.

It is a unique 16-bit number that identifies each DNS query. This number is randomly generated for each query. It ensures that the response is associated with the correct query. The /etc/init.d/bind9 restart command can flush the DNS cache.

A local storage for recently resolved host names and their corresponding IP addresses. It helps speed up resolving requests for frequently accessed domains. The cache is usually cleared or refreshed automatically after a certain period of time.

It is a service that acts as a central database for resolving domain names to IP addresses. It uses a hierarchical structure, with root servers at the top and authoritative servers for individual domains at the bottom. BIND is a popular DNS server implementation.

A technique that allows attackers to manipulate DNS responses to redirect users to malicious websites or intercept sensitive data. It exploits vulnerabilities in DNS server configurations and can be used for phishing, malware distribution, and other malicious activities.

A security measure that uses digital signatures to verify the authenticity and integrity of DNS responses. DNSSEC helps prevent DNS cache poisoning by ensuring that the responses are from trusted sources.

This occurs when a user's browser is redirected to a malicious website after an attacker corrupts a domain nameserver (DNS) with illegitimate IP addresses for certain hostnames.

a sub-domain can be delegated by its parents to other servers. This allows for flexibility within the DNS namespace and increases redundancy.

Multiple name servers are used to handle domain lookups. This prevents single points of failure and improves DNS server availability. They are often set up as master and slave servers.

This is a security issue tied to the Transaction ID that could allow an attacker to insert false information into a DNS server's cache. It's particularly vulnerable in older versions of BIND where the ID wasn't truly random.

BIND , short for Berkeley Internet Name Daemon, is a widely used implementation of the Domain Name System (DNS). This software manages DNS servers, resolves domain names into IP addresses, and provides various tools for interacting with DNS.

This refers to the process by which a DNS server responds to a DNS query. It's based on the configuration files that dictate how the server handles requests and where it retrieves the necessary information.