Getting a DNS TXT record in Ruby

Question

I need to get the txt field from the DNS record.
Is there any ruby api to do something like this?

nslookup -q=txt xxxx.com

Answer 1

Use the Ruby stdlib Resolv::DNS library without installing a gem:

require 'resolv'
txt = Resolv::DNS.open do |dns|
  records = dns.getresources("_dmarc.yahoo.com", Resolv::DNS::Resource::IN::TXT)
  records.empty? ? nil : records.map(&:data).join(" ")
end
#=> "v=DMARC1; p=reject; sp=none; pct=100; rua=mailto:[email protected], mailto:[email protected];"

getresources returns an array of instances of the requested record class name (Resolv::DNS::Resource::IN::TXT). Here, I return nil if the TXT record(s) or the host name were not found, otherwise I map over the records, call data to get the values, then join them together.

Any DNS record type [TXT, NS, CNAME, MX, ...] can be queried as well by replacing TXT in the above example.

TXT records are "unstructured" and used for enhanced data for the hostname such as SPF, DKIM, DMARC configurations. In practice, there may be only one TXT record, but the RFC doesn't say how many there can be.

Read the docs at: http://www.ruby-doc.org/stdlib-2.1.1/libdoc/resolv/rdoc/index.html