DNS Resource Record Types

Shuvro

DNS resource records can be used to provide DNS-based data about computers on a TCP/IP network. Well I don’t know if there is a network other than TCP/IP network, other than the internal isolated lab network for engineering purposes. Anyway, the following are some primary resource records currently we work with:

  • SOA: Start of Authority locates the zone.
  • NS: NS records specify the authoritative name server for a domain.
  • A: Address records direct a hostname to a numerical IP address.
  • PTR: Pointer Records are used for reverse lookups, IP to domain or hostname.
  • CNAME: Canonical Name allows a machine to be known by one or more hostnames
  • MX: Mail Exchanger records are used to help route email according the domain owners preference
  • SRV: Service resource records enable you to specify the location of the servers for a specific service, protocol, and DNS domain (copy & paste from TechNet article, see below link for the whole description)

For further understanding of record composition, checkout the following links:

https://en.wikipedia.org/wiki/List_of_DNS_record_types

https://technet.microsoft.com/en-us/library/cc958958.aspx

Sharing a typical Example where the Office 365 cloud service records are required and those are as follows:

MX records

Priority Host name Points to address or value TTL
0 @ link3-net.mail.protection.outlook.com 3600

CNAME records

Host name Points to address or value TTL
autodiscover autodiscover.outlook.com 3600
sip sipdir.online.lync.com 3600
lyncdiscover webdir.online.lync.com 3600
msoid clientconfig.microsoftonline-p.net 3600
enterpriseregistration enterpriseregistration.windows.net 3600
enterpriseenrollment enterpriseenrollment.manage.microsoft.com 3600

TXT records

TXT name TXT value TTL
@ v=spf1 include:spf.protection.outlook.com -all 3600

SRV records

Service Protocol Port Weight Priority Name Target TTL
_sip _tls 443 1 100 @ sipdir.online.lync.com 3600
_sipfederationtls _tcp 5061 1 100 @ sipfed.online.lync.com 3600