4 files changed, 35 insertions, 13 deletions
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index 5aed0c9358..c59affea8f 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -25,9 +25,8 @@ If you're upgrading an existing application, it's a great idea to have good test
 coverage before going in. You should also first upgrade to Rails 4.1 in case you
 haven't and make sure your application still runs as expected before attempting
 to upgrade to Rails 4.2. A list of things to watch out for when upgrading is
-available in the
-[Upgrading Ruby on Rails](upgrading_ruby_on_rails.html#upgrading-from-rails-4-1-to-rails-4-2)
-guide.
+available in the guide: [Upgrading Ruby on
+Rails](upgrading_ruby_on_rails.html#upgrading-from-rails-4-1-to-rails-4-2)
 
 
 Major Features
@@ -36,9 +35,12 @@ Major Features
 ### Active Job, Action Mailer #deliver_later
 
 Active Job is a new framework in Rails 4.2. It is an adapter layer on top of
-queuing systems like [Resque](https://github.com/resque/resque), [Delayed Job](https://github.com/collectiveidea/delayed_job), [Sidekiq](https://github.com/mperham/sidekiq), and more. You can write your
-jobs with the Active Job API, and it'll run on all these queues with no changes
-(it comes pre-configured with an inline runner).
+queuing systems like [Resque](https://github.com/resque/resque), [Delayed
+Job](https://github.com/collectiveidea/delayed_job),
+[Sidekiq](https://github.com/mperham/sidekiq), and more.
+
+You can write your jobs with the Active Job API, and it'll run on all these
+queues with no changes (it comes pre-configured with an inline runner).
 
 Building on top of Active Job, Action Mailer now comes with a `#deliver_later`
 method, which adds your email to be sent as a job to a queue, so it doesn't
@@ -52,11 +54,16 @@ deserialize it at run time.
 
 ### Adequate Record
 
-Adequate Record is a set of refactorings that make Active Record `find` and `find_by` methods and some association queries upto 2x faster.
+Adequate Record is a set of refactorings that make Active Record `find` and
+`find_by` methods and some association queries upto 2x faster.
 
-It works by caching SQL query patterns while executing the Active Record calls. The cache helps skip parts of the computation involved in the transformation of the calls into SQL queries. More details in [Aaron Patterson's post](http://tenderlovemaking.com/2014/02/19/adequaterecord-pro-like-activerecord.html).
+It works by caching SQL query patterns while executing the Active Record calls.
+The cache helps skip parts of the computation involved in the transformation of
+the calls into SQL queries. More details in [Aaron Patterson's
+post](http://tenderlovemaking.com/2014/02/19/adequaterecord-pro-like-activerecord.html).
 
-Nothing special has to be done to activate this feature. Most `find` and `find_by` calls and association queries will use it automatically. Examples:
+Nothing special has to be done to activate this feature. Most `find` and
+`find_by` calls and association queries will use it automatically. Examples:
 
 ```ruby
 Post.find 1  # caches query pattern
@@ -177,6 +184,21 @@ class UsersController < ApplicationController
 end
 ```
 
+### Default host for `rails server`
+
+Due to a [change in Rack](https://github.com/rack/rack/commit/28b014484a8ac0bbb388e7eaeeef159598ec64fc),
+`rails server` now listens on `localhost` instead of `0.0.0.0` by default. This
+should have minimal impact on the standard development workflow as both http://127.0.0.1:3000
+and http://localhost:3000 would continue to work as before on your own machine.
+
+However, with this change you would no longer be able to access the Rails server
+from a different machine (e.g. your development environment is in a virtual
+machine and you would like to access it from the host machine), you would need
+to start the server with `rails server -b 0.0.0.0` to restore the old behavior.
+
+If you do this, be sure to configure your firewall properly such that only
+trusted machines on your network can access your development server.
+
 ### Production logging
 
 The default log level in the `production` environment is now `:debug`. This
@@ -322,7 +344,7 @@ Please refer to the [Changelog][railties] for detailed changes.
       namespace: my_app_development
 
     # config/production.rb
-    MyApp::Application.configure do
+    Rails.application.configure do
       config.middleware.use ExceptionNotifier, config_for(:exception_notification)
     end
     ```
diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index 7b3081993d..f2831defe6 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -138,7 +138,7 @@ You can easily change your adapter:
 ```ruby
 # be sure to have the adapter gem in your Gemfile and follow the adapter specific
 # installation and deployment instructions
-YourApp::Application.config.active_job.queue_adapter = :sidekiq
+Rails.application.config.active_job.queue_adapter = :sidekiq
 ```
 
 
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 667281d1aa..220946e8d5 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -108,7 +108,7 @@ numbers. New applications filter out passwords by adding the following `config.f
 
 * `config.log_formatter` defines the formatter of the Rails logger. This option defaults to an instance of `ActiveSupport::Logger::SimpleFormatter` for all modes except production, where it defaults to `Logger::Formatter`.
 
-* `config.log_level` defines the verbosity of the Rails logger. This option defaults to `:debug` for all modes except production, where it defaults to `:info`.
+* `config.log_level` defines the verbosity of the Rails logger. This option defaults to `:debug` for all environments.
 
 * `config.log_tags` accepts a list of methods that the `request` object responds to. This makes it easy to tag log lines with debug information like subdomain and request id - both very helpful in debugging multi-user production applications.
 
diff --git a/guides/source/debugging_rails_applications.md b/guides/source/debugging_rails_applications.md
index 88c6210296..1a647f8375 100644
--- a/guides/source/debugging_rails_applications.md
+++ b/guides/source/debugging_rails_applications.md
@@ -138,7 +138,7 @@ Rails.logger.level = 0 # at any time
 
 This is useful when you want to log under development or staging, but you don't want to flood your production log with unnecessary information.
 
-TIP: The default Rails log level is `info` in production mode and `debug` in development and test mode.
+TIP: The default Rails log level is `debug` in all environments.
 
 ### Sending Messages