DNS (Domain Name System) Flashcards
What is DNS?
NS (Domain Name System) is a system that translates human-readable domain names into IP addresses.
What is the purpose of DNS?
DNS allows users to access websites and services using human-readable domain names instead of numeric IP addresses.
What types of DNS records exist?
Common DNS records include A, AAAA, CNAME, MX, TXT, and PTR records.
What is an A record in DNS?
An A (Address) record maps a domain name to an IPv4 address.
What is a CNAME record used for?
A CNAME (Canonical Name) record maps an alias or subdomain to the canonical domain name.
What does TTL mean in DNS?
TTL (Time to Live) indicates how long a DNS record is cached by resolvers before it expires and must be refreshed.
What is a reverse DNS lookup?
A reverse DNS lookup translates an IP address into a domain name, typically using a PTR record.
What is the role of the authoritative DNS server?
The authoritative DNS server holds the definitive DNS records for a domain and responds to queries with the correct IP addresses.
What is the difference between an A and an AAAA record?
An A record maps a domain to an IPv4 address, while an AAAA record maps a domain to an IPv6 address.
How do DNS resolvers work?
DNS resolvers query DNS servers to resolve domain names to IP addresses. They start by checking their cache and then query other DNS servers if needed.
What is an MX record used for?
An MX (Mail Exchange) record specifies the mail server responsible for receiving email for a domain.
What is DNS caching?
DNS caching stores DNS query results to improve performance and reduce the load on DNS servers by temporarily saving resolved addresses.
What is a zone file in DNS?
A zone file contains DNS records for a specific domain and is managed by the authoritative DNS server.
What happens when a DNS query times out?
If a DNS query times out, the resolver retries the request to other DNS servers or returns an error.
What is a DNS resolver?
A DNS resolver is a server or service that queries DNS databases to find IP addresses associated with domain names.
