💻 IT Tools & References

Subnet calculator, base converter, HTTP status codes, port reference

🌐 IP Subnet Calculator

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🔢 Number Base Converter

Decimal255
Binary1111 1111
HexadecimalFF
Octal377
ASCII

📋 HTTP Status Codes

200

OK

Request succeeded

2xx
201

Created

Resource created successfully

2xx
204

No Content

Success, no body returned

2xx
206

Partial Content

Range request fulfilled

2xx
301

Moved Permanently

Resource moved, update bookmark

3xx
302

Found

Temporary redirect

3xx
304

Not Modified

Cached version is still valid

3xx
307

Temporary Redirect

Redirect, keep same method

3xx
400

Bad Request

Malformed request syntax

4xx
401

Unauthorized

Authentication required

4xx
403

Forbidden

Server refuses to authorize

4xx
404

Not Found

Resource does not exist

4xx
405

Method Not Allowed

HTTP method not supported

4xx
408

Request Timeout

Client took too long

4xx
409

Conflict

Request conflicts with current state

4xx
410

Gone

Resource permanently removed

4xx
422

Unprocessable Entity

Validation error

4xx
429

Too Many Requests

Rate limit exceeded

4xx
500

Internal Server Error

Unexpected server error

5xx
501

Not Implemented

Feature not supported by server

5xx
502

Bad Gateway

Invalid response from upstream

5xx
503

Service Unavailable

Server temporarily down

5xx
504

Gateway Timeout

Upstream server timed out

5xx

🔌 Common Port Numbers

PortNameProtocolUsage
20FTP DataTCPFile Transfer Protocol — data
21FTP ControlTCPFile Transfer Protocol — control
22SSHTCPSecure Shell remote login
23TelnetTCPUnencrypted remote access (deprecated)
25SMTPTCPEmail sending (outbound)
53DNSTCP/UDPDomain Name System lookups
67DHCP ServerUDPDynamic IP assignment
80HTTPTCPUnencrypted web traffic
110POP3TCPEmail retrieval (older)
143IMAPTCPEmail retrieval (sync)
194IRCTCPInternet Relay Chat
443HTTPSTCPEncrypted web traffic (TLS)
465SMTPSTCPEncrypted email sending
587SMTP SubTCPEmail submission (STARTTLS)
993IMAPSTCPEncrypted IMAP email
995POP3STCPEncrypted POP3 email
1433MSSQLTCPMicrosoft SQL Server
3306MySQLTCPMySQL database
3389RDPTCPRemote Desktop Protocol
5432PostgreSQLTCPPostgreSQL database
5900VNCTCPVirtual Network Computing
6379RedisTCPRedis in-memory database
8080HTTP AltTCPAlternate HTTP, dev servers
8443HTTPS AltTCPAlternate HTTPS
27017MongoDBTCPMongoDB database