DNS - Record

A DNS record is a row in a DNS database.

A record is a text line.

<name> <ttl> <class> <type> <rdata>

• name is the name or IP address for a ptr record
• ttl is the the time to live in the cache
• class is the network class being used. No more used only for compatiblity
  • IN for Internet (The default and only)
  • HS for Hesiod (deprecated)
  • CH for Chaosnet (deprecated)
• type is the type of record
• rdata is output of the lookup

Example of a A record.

api                                 IN A      164.132.99.202

where:

• api is a relative name
• IN is the INTERNET class (An other value is ANY)
• A is the A record
• 164.132.99.202 is the Ip address

If the apex domain is example.com, this entry will point the qualified domain name api.example.com to the ip 164.132.99.202

Pointer record match a name to a destination

• An A record maps a domain name to an IP address Version 4
• An AAAA'' record maps a domain name to an IP address Version 6.
• The NS record determines your DNS server - nameserver,
• CNAME - name to name alias
• ALIAS - name to ip alias
• PTR - reverse

• CAA
• TXT
• NAPTR
• SRV Record (Service AutoDiscovery)
• LOC
• SSHFP
• TLAS

• DNS - MX record (Mail Exchanger Record) - point to the mail server,
• SRV Record (Service AutoDiscovery) for email autodicovery

There is also a TXT record for each of the following mail authentication mechanism.

• Email - Sender Policy Framework (SPF)
• Email - DomainKeys Identified Mail (DKIM) - Mail Signatures
• Email - DMARC (Domain-based Message Authentication)

• ANY,
• SOA,

With nslookup if we want to see the TXT record

nslookup -type=TXT bytle.net

Server:  amplifi.lan
Address:  192.168.135.1

Non-authoritative answer:
bytle.net       text =

        "v=spf1 a include:vps748761.ovh.net -all"

Network - dig ( DNS tool)

dig -t TXT DOMAIN

The Time To Live (TTL) of a DNS record is generally of 5 minutes.

If clients cache the results of host name lookups in order to achieve a performance improvement, they MUST observe the TTL information reported by DNS. Ref - DNS Spoofing

• List_of_DNS_record_types