There are five website status groups in total - 1xx, 2xx, 3xx, 4xx and 5xx. And the 2xx group of encoded messages is about successful completion of the operation requested by the client (user). Therefore, every status message in this group represents the status of completion, additional requirements for completion or various issues in completion. Basically, every accomplished client’s query ends with one of the answers from this group if the server works as intended.
Starting from the 200 response code, every number inside the category defines the circumstances that the client’s query was finished after the acquisition and going through all necessary procedures on the host. But the explanations inside the encoded reaction messages could differentiate according to particular situations and circumstances. For starters, status code 200 meaning tells webmasters that literally everything operated as intended upon client’s query and nothing more.
Following this logic, 201 is an answer to the creation of the new web instance on the host. And code 204 or “No Content” notifies about the fact that the operation has reached the host, was acquired and finished, but the resource has nothing to react with. Taking this into account, it is vital to learn about various reactions in the 2xx group to get the knowledge about what those are responsible for.
Status code 200 OK
Basically, the answer, despite having only two actual letters of explanation, already defines and explains everything that everyone should know. It literally states that every sequence works literally by the book; the query was acquired, all the steps were finished as per the procedure and all the necessary data was sent in return as a response. Client side gets the 200 status code in all circumstances and cases in which the website or another web instance promptly loads and shows necessary data as per whatever action the user had taken.
To keep it simple, what status code 200 means basically defines circumstances when every single thing went as it should. The query finished all necessary steps for completion - was executed, reached its destination, acquired, comprehended and completed without any possible issues or errors. And in any other possible case the webmaster won’t get the response code 200 in logs - there will be a different answer to the initial query.
Web resource reactions via encoded messages could be from the 2xx group or from another one, and it will depend on the performance, software, hardware, network state and other circumstances. Moreover, most users usually don’t see an ‘OK’ and it’s visible only when the webmaster is trying to diagnose something by executing an operation without trying to access actual data.
201 status code - ‘Created’
This answer appears only when the user or, commonly, the webmaster, creates a new web resource on the host. This 201 response code is literally about the creation of the new instance on the web host and about the fact that it was accomplished without issues. And, of course, about the fact that no additional queries are necessary. Therefore, in the same manner as with the 200, it’s commonly unseen on the client side and commonly could be seen only in server logs when conducting diagnostics.
Only in certain circumstances, like when the client has the administrative access rights for web instance creation or uses other tools that can grant a similar degree of authority, even temporarily, status code 201 could be seen if the host allows it upon finishing the creation task. Otherwise it’s unseen at all except in host logs - commonly the browser or other client-side software follows the host-issued sequence to redirect the software to the newly created web instance, but it highly varies and depends on the configuration and circumstances.
201 vs 200 status code
Basically, both primary encoded notifications from the 2xx group are returned in reply to successful operation of the web host following the client query. But comparison of status code 201 vs 200 is not valid when looking deeper into their definition and explanation.
200 literally defines that processing of getting data from the web source was accomplished and the client side received the data in return, as per the client-sent query. On the other hand, 201 defines that the host returned the message about the successful creation, for example, of the web instance (page or file, for example) on the same host. Therefore, the webmaster or the client side will see ‘OK’ on access attempt and ‘Created’ on creation query accordingly.
202 status code - ‘Accepted’
One of the most common reactions from the 2xx category of notifications from the host that the one could possibly get. It only could be seen in the circumstances when the query was not accomplished upon being received by the host immediately. Usually, 202 response code refers to circumstances when the user commits a query that imply immediate finalization of the procedure or fetching an immediate answer from the host.
This could happen if the batch uploading of files to the host is needed, and in such circumstances all uploading queries except the active one will return the status code 202 as per the instructions from the host. This happens because all queries were queued for further processing. And, accordingly, the client will get encoded messages for each separate query in order of completion.
In other words, this is a message meant for asynchronous operations. It precedes other encoded messages, indicating that all queries were queued for completion by the host but not processed and therefore completion responses were not sent.
203 status code - ‘Non-Authoritative Information’
This encoded message is issued by the host only in circumstances when the client side is connected to the network through the proxy and tries to send a query to the web host in the similar manner. And it defines that the data was changed due to the usage of the said proxy, and it won’t be considered as authoritative by the client-host synchronization sequence. Simply put, status code 203 appears when the proxy somehow modifies the successful answer due to its configuration and changes its overall integrity and validity.
Usually, the 203 response code has the highest degree of importance for procured operation of the web instance. Because it was deemed necessary by the host-side to notify the client-side software about the changes inside the internal structure of the requested data. This defines that this data shouldn’t be cached. And it’s important to avoid cached data mismatches. In such circumstances cached parts of the source must be renewed after removing the proxy from configuration.
204 status code - ‘No Content’
This is basically an answer for correct operation of the host with no data to show or add. Nowadays, 204 response code commonly appears when working with various editing interfaces - for instance, text editors. And when it appears in logs, it means that the data wasn’t modified during interaction, therefore, the hosting has nothing to add to the current data.
Basically, status code 204 is the method utilized by the host for notifying the client about the unchanged condition of the info it operates upon query. And it’s commonly used as a way to notify that info was sent, fetched and acquired, query was completed, everything works normally but nothing in the current data was marked as even possibly changed by the client.
Status code 204 no content usage
Usually, the 204 ‘No Content’ message is used when confirming the save request from the client side that’s accessing the editing interface. For instance, when the user uses the Google Docs and it tries to autosave the document, the client (user's browser) gets the 204 return to its autosaving requests when nothing inside the document was changed by the client.
Also, it is widely used as the resource reaction for automated systems working with data transferring functionality. And it works in basically the same way as was described above, although the message with 204 appears when no data on the receiving end was changed.
205 status code - ‘Reset Content’
This web-host answer notifies that the resource accomplished the handling of the user’s query and the web instance state must be reset by the host upon finishing. Usually the status code 205 appears when, for starters, the web instance with the form or the document, is refreshed by the client side under condition to be reversed to the unchanged iteration. It notifies that the aforementioned form will be renewed and reversed to its unchanged version.
Basically, 205 response code is sent by the host whenever the web instance was configured to reset upon refresh query. Another way to see this notification message from the server is when its configuration defines the condition to to reset the instance upon submitting the data that was filled into, for example, the form or the document.
206 status code - ‘Partial Content’
This is the encoded message that usually appears when the client is downloading the data from the host upon the range requests. The status code 206 notifies about situations when only some part of the requested data will be acquired by the user as soon as the query is accepted. And, obviously, it defines the circumstances when the host can handle only a single part of the range and is able to send it upon finishing the task. During downloading there could be several messages with the 206 response code, basically stating that everything works as intended.
From the technical standpoint, there are three types of 206 messages, depending on the settings - Single Part, Multiple Parts and Combined Parts. Those represent transferring of a single part of the data, simultaneous transfer of several parts or transferring of a combined data stack due to the similar conditions of adjacent queries in the queue.
207 status code - ‘Multi-Status’
This is a message that covers situations when the user’s query was accepted but prompted more than a single reaction from the host and they were combined in a single answer from the host. The status code 207 appears whenever the host reacts to batch query completion, the host finds more than a single source or data entries to present as an answer, and when the query completion fulfills conditions for several different responses.
Basically, the 207 response code is a means for the resource to combine more than one resource reaction code into one message. Therefore, the client should check all of the included encoded messages manually if necessary.
Status code 221
When the user is faced with the 221 response code, it means that it’s the answer to a query via FTP or SMTP protocol - to file or mail servers respectively. And the same web host answer remains unsupported by HTTP protocol.
In the case of FTP it’s simple - the status code 221 means that the user’s attempt to close the session was a success. Therefore, the connection with the FTP resource was defined as closed.
In the case of the SMTP reaction with the status code 221, it’s an internal mail resource notification method that has two meanings. One literally designates the end of the session, just like FTP-related one. And another is the authentication issue due to client-side username or password mismatch. To fix the latter, the user should check the username and password provided to access the mail resource.
Status code 222
This is an unsupported message number for HTTP protocol, but an error return for SNMP protocol. The status code 222 is a message for webmasters with ‘No such object’ message as an answer to the query and it’s not too easy to fix, because Object ID or OID varies depending on the hardware vendor.
Basically, 222 response code states that no object with the ID stated by the webmaster’s query was found on the host, therefore the operation could not be completed and host returned with the error. To make the query successful, the webmaster should double-check the object ID to make sure everything was made properly.
Status code 223
Unsupported answer for HTTP and one wouldn’t see it when working with the website. But this is a very important error for webmasters working with SNMP protocol and mail servers. And it’s an alternative to the host downtime, because it states that the hardware is inaccessible.
Basically, SNMP status code 223 or error 223 is an answer from a related software that defines that no connection with the host could be established due to designated hardware instances not being found. And, obviously, no content is designated as unfound as well. Or, in other words, the host is inaccessible, therefore the webmaster sees the 223 response code via monitoring software or when trying to access the host.
Status code 225
This number is unsupported by HTTP protocol. But the encoded notification with this particular number is an internal reaction for the FTP hosts. And it defines the circumstances when the client-host connection is opened and stable, but nothing is currently transferring between the two. Basically, ‘the connection is established, but without any data transfer’ is the literal explanation of this message.
The status code 225 notifies that no problem is occurring on either side and everything is ready for uploading or downloading the data to the host side or to the client side respectively. Therefore, the 225 response code for FTP protocol means almost the same as the 200 ‘OK’ means for HTTP protocol. Seeing this message, the user could start managing the data on the file host without any issues, and will acquire other encoded messages afterwards.
Status code 227
Unsupported by an HTTP, this reaction is related to FTP messages and it basically means that the host is in a passive mode and it’s ready for establishing a network link with the client. This status code 227 also includes additional information and has a set of particular parameters inside -the port and the IP that the host is listening to.
Those values are very important, because 227 response code literally contains the info that is necessary for client side software for established connection to the host. And it only appears if the client side software is capable enough to parsing the aforementioned data values and processing them - h1 to h4 for listened IP addresses and h1 to h2 for the listened ports.
Status code 228
This answer is basically an FTP alternative for 408 ‘Request Timeout’ HTTP code. There’s no supported message with such a number for HTTP, and FTP-related one has its own specifics. In a nutshell, the status code 228 message says ‘Entering Long Passive Mode’, and it means literally what it says - the connection is established, everything works normally, but the operation sequence was not answered due to the long processing by the resource.
Usually this message appears when something is wrong with the configuration. It’s either the wrong setup of the passive port range on the file hosting side or a badly configured firewall on the client side. Both of those could prevent the proper data transfer and result in the 228 response code appearing.
What is 204 status code
This is the answer for cases when the user tried to edit something, usually documents, but still made no changes. Therefore the host literally has nothing to send back as an update upon action from the client. Usually appears during autosave sequences due to the unchanged state of the instance (file, table, document and so on)..
What is status code 200
This is the most basic HTTP answer to any user’s query when everything works normally and without any issues. It states that the host is working normally and the client side action was completed upon query - it was sent, fetched and acquired, and then the return data was sent back by the host.
What is response code 206
This answer states that the data designated for downloading by the user-side device was cut into several independent parts for transfer. Following this server-side operation, all designated parts were queued for transfer in accordance with the defined order and will be transferred to the user-side in accordance with this queue.
What is response code 202
This answer is the alternative to ‘OK’ for cases when a client's query was designated to be delayed or several actions were queued for completion. For starters, the most common circumstances for it is when the client is trying to load a web instance (page or application) full of heavy content that obviously couldn’t be loaded simultaneously. Usually this answer is followed by another one upon completion.
What is response code 201
This encoded message appears in situations when the new instance was created on the host following the client’s query . In other words, it appears when the user created the new web page, database entry and so on. Basically, is an alternative to ‘OK’ for cases when the client side executed ‘write’ instead of ‘read’ needed for 200 to appear.