EC
SocketError
RubyERRORNotableNetwork

Socket or hostname resolution failure

Quick Answer

Verify the hostname is correct, DNS is reachable, and rescue SocketError alongside Errno network errors.

What this means

Raised for high-level socket errors, most commonly hostname resolution failures (getaddrinfo). SocketError is a subclass of StandardError and wraps errors from the socket library that are not mapped to Errno:: constants.

Why it happens
  1. 1Hostname cannot be resolved (typo, DNS failure, no network)
  2. 2getaddrinfo returns an error for the specified host/service

Fix

Rescue with context and validate hostnames

Rescue with context and validate hostnames
require 'resolv'

def resolvable?(host)
  Resolv.getaddress(host)
  true
rescue Resolv::ResolvError
  false
end

Why this works

Resolv.getaddress pre-checks DNS resolution without opening a socket.

Code examples
Reproducing the errorruby
require 'socket'
TCPSocket.new('this.host.does.not.exist', 80)
# SocketError: getaddrinfo: Name or service not known
Rescue SocketErrorruby
begin
  Net::HTTP.get(URI('http://badhost.example/'))
rescue SocketError => e
  puts "DNS failure: #{e.message}"
end
Full network error rescueruby
rescue SocketError, Errno::ECONNREFUSED, Errno::ETIMEDOUT => e
  raise NetworkError, e.message
Sources
Official documentation ↗

Ruby Standard Library Documentation

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