DNS - Record

Map Of Internet 1973


A DNS record is a row in a DNS database.


Example of a A record.

api                                 IN A


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


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




Pointer records that match a name to a destination:

  • ALIAS - Name to ip alias
  • PTR - reverse - from IP to name



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


  • ANY,
  • SOA,


A query is also known as a lookup. Check the lookup page to known how to perform a query.

Time To Live (TTL)

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 2)

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Map Of Internet 1973
AAAA DNS record

A AAAA DNS record maps a domain name to a IPV6 address
Map Of Internet 1973
DNS - nslookup command line

Nslookup is a DNS client program to query (ie lookup) domain name servers and get back DNS record information nslookuphost fileping Nslookup has two modes: The local DNS file is /etc/resolv.conf...
Map Of Internet 1973
DNS Alias record

An alias is a DNS record with a name that resolves directly to an ip_address. cnamenamenamean ip addressDNS resolverroundtripip_addressCNAME Before creating an ALIAS record, check there are no: ...
Map Of Internet 1973
DNS Database

The DNS database is the DNS repository that contains all DNS record of a domain The domain provider should have a graphical interface to modify records but at the end, this record are stored in a text...
Map Of Internet 1973
Data Cache - Time to Live (TTL) or hop limit

The TTL is the maximum timespan of data in a cache. Once the timespan has elapsed, data is discarded or revalidated. A DNS record has a TTL attached A HTTP cache with the max-age and s-max-age...
Domain Validate Certificate
Domain Validated Certificates (DV)

Domain Validated certificates are server signed certificates where the ownership of the domain was checked. There is no identifying organizational information for these certificates and thus should never...
Map Of Internet 1973
Network - (Internet) Apex Domain (also known as Zone domain)

An apex domain is the domain name that: is composed of the two top-level label of a name (the first being the top level domain) does not contain a subdomain For example: example.com is an apex domain....
Map Of Internet 1973
Network - DNS Lookup (Request|query)

A DNS lookup is a request to a DNS server in order to get DNS record from a DNS name a A query will get you a ipv4 address a AAAA query will get you the ipv6 address a TXT query will get your a...
Map Of Internet 1973
Network - Fully Qualified Domain Name (FQDN)

FQDN stands for fully qualified domain name. It's a name that is said to be absolute (ie that includes the local domain and ends with a dot). This name identifies uniquely a node in the namespace....
Map Of Internet 1973
SRV Record (Service AutoDiscovery)

SRV are DNS records that defines connection information of a service (Autodiscover) Email: They enable an email client software to be automatically configured for your email account .

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