3 types of DNS queries—recursive, iterative, and non-recursive. 3 types of DNS servers—DNS Resolver, DNS Root Server and Authoritative Name Server.
How many queries are there in DNS?
There are three basic DNS queries in a standard DNS lookup. Recursive query: In a recursive query the computer requests an IP address or the confirmation that the DNS server doesn’t know that IP address.
What is a DNS any query?
An ANY query is a type of DNS query that retrieves all records available for a domain name. The ANY query must be sent to a name server that is authoritative for a domain.
What is DNS recursive query?
What is recursive DNS? A recursive DNS lookup is where one DNS server communicates with several other DNS servers to hunt down an IP address and return it to the client. This is in contrast to an iterative DNS query, where the client communicates directly with each DNS server involved in the lookup.
What are the types of DNS zones?
There are two types of DNS zones – Primary (Master) DNS zone for control and Secondary (Slave) DNS zone for redundancy and better performance. The first contains all the original DNS records, and the second gets them from the Primary DNS zone. The process is called DNS zone transfer.
What FQDN means?
A fully-qualified domain name (FQDN) is that portion of an Internet Uniform Resource Locator (URL) that fully identifies the server program that an Internet request is addressed to.
What is TTL DNS?
DNS TTL (time to live) is a setting that tells the DNS resolver how long to cache a query before requesting a new one. The information gathered is then stored in the cache of the recursive or local resolver for the TTL before it reaches back out to collect new, updated details.
What is A record and Cname in DNS?
A Canonical Name or CNAME record is a type of DNS record that maps an alias name to a true or canonical domain name. CNAME records are typically used to map a subdomain such as www or mail to the domain hosting that subdomain’s content.
What is the format of DNS query and response message?
DNS has two types of messages: query and response. Both types have the same format. The query message consists of a header and question records; the response message consists of a header, question records, answer records, authoritative records, and additional records (see Figure4).
What is DNS zone example?
DNS zones are not necessarily physically separated from one another, zones are strictly used for delegating control. For example, imagine a hypothetical zone for the cloudflare.com domain and three of its subdomains: support.cloudflare.com, community.cloudflare.com, and blog.cloudflare.com.
Where is the DNS server located?
Open your Command Prompt from the Start menu (or type “Cmd” into the search in your Windows task bar). Next, type ipconfig/all into your command prompt and press Enter. Look for the field labeled “DNS Servers.” The first address is the primary DNS server, and the next address is the secondary DNS server.
How do I read DNS records?
The most efficient way to check DNS records of the domain is to use a terminal with the command nslookup. This command will run on almost all operating systems (Windows, Linux, and macOS).
What is the port 53?
DNS uses Port 53 which is nearly always open on systems, firewalls, and clients to transmit DNS queries. Rather than the more familiar Transmission Control Protocol (TCP) these queries use User Datagram Protocol (UDP) because of its low-latency, bandwidth and resource usage compared TCP-equivalent queries.
What is a query in network?
Definition. In-Network query processing refers to the complete or partial evaluation of database queries at the edges of a network, rather than in a centralized database server.
What happens if a DNS reply exceeds 512 bytes?
To comply with DNS standards, responses sent over UDP are no more than 512 bytes in size. Responses exceeding 512 bytes are truncated and the resolver must re-issue the request over TCP.
What is AAAA DNS record?
An AAAA record maps a domain name to the IP address (Version 6) of the computer hosting the domain. An AAAA record is used to find the IP address of a computer connected to the internet from a name.
What is the format of DNS query and response message?
DNS has two types of messages: query and response. Both types have the same format. The query message consists of a header and question records; the response message consists of a header, question records, answer records, authoritative records, and additional records (see Figure4).
What is iterative and recursive?
Recursion is when a function calls itself within its code, thus repeatedly executing the instructions present inside it. Iteration is when a loop repeatedly executes the set of instructions like “for” loops and “while” loops.
How do I know if my DNS is recursive?
Use dig and check the status of the RD and RA bits in the response. By default dig will send a recursive query ( RD set in the query header) unless you set the +norecurse command line flag. If the server supports recursive queries the response will have the “recursion available” RA bit set in the response headers.
What is primary DNS server?
A primary DNS server is the first point of contact for a browser, application or device that needs to translate a human-readable hostname into an IP address. The primary DNS server contains a DNS record that has the correct IP address for the hostname.
What is DNS file system?
The Domain Name System (DNS) is the hierarchical and decentralized naming system used to identify computers reachable through the Internet or other Internet Protocol (IP) networks. The resource records contained in the DNS associate domain names with other forms of information.
What is the difference between zone and domain?
A “domain” represents the entire set of names / machines that are contained under an organizational domain name. For example, all domain names ending with “.com” are part of the “com” domain. A “zone” is a domain less any sub-domains delegated to other DNS servers (see NS-records).
