Comptia A+ 1101 DNS & DNS Records

DNS (Domian Name System)

- translates human-readable domain names into computer-readable IP addresses
- made of multiple, hierchial servers
- distributed database

RR (Resource Records)

- database records of DNS
- over 30 record types

A (Adress Records) (AAAA)

A Records:
- IPv4
- modify to change the host name to IP address resolution

AAAA Records:
- IPv6
- the same DNS server, different records (modify to change the host name to IP address resolution)

Mail Exchanger Record (MX)

determines the host name for the mail server

Text Records (TXT)

- human-readable text information
- useful public information
- can be used for verification purposes or email security
- use "dig [website name] txt" in cmd prompt to view (or, "nslookup -type=txt [website name/domain name]" when dig isn't available)

Time To Live (TTL)

specifies how long an end station will remember the match between a fully qualifies domain name and IP address

Sender Policy Framework (SPF)

- a list of all the email servers that are authorized to send messages using your fully qualified domain name
- prevents spoofing (mail servers perform a check to see if incoming mail really did come from an authorized host)

Domain Keys Identified Mail (DKIM)

- digitally signs a domain's outgoing mail
- valuated by mail servers (not usually seen by the end-user)
- the public key is stored in the DKIM TXT record

Domain-Based Message Authentication, Reporting, and Conformance (DMARC)

- prevents unauthorized email use and spoofing
- an extension of SPF and DKIM
- takes the extra step to determine the disposition that should be used when someone receives a message that cannot be validated