HEAD and OPTIONS methods in Rest API - Step-by-Step Execution

Concept Flow - HEAD and OPTIONS methods

Client sends OPTIONS request

↓

Server responds with allowed methods

↓

Client sends HEAD request

↓

Server responds with headers only

↓

Client processes headers without body

The client first asks the server which methods are allowed using OPTIONS, then requests headers only with HEAD, receiving no body.

Execution Sample

Rest API

OPTIONS /resource HTTP/1.1
Host: example.com

HEAD /resource HTTP/1.1
Host: example.com

Client sends OPTIONS to check allowed methods, then HEAD to get headers without body.

Execution Table

Step	Request Method	Request Target	Server Action	Response Content	Notes
1	OPTIONS	/resource	Check allowed methods for /resource	Headers with Allow: GET, POST, HEAD, OPTIONS	Client learns allowed methods
2	HEAD	/resource	Retrieve headers for /resource	Headers only, no body	Client gets metadata without content
3	-	-	-	-	No body sent in HEAD response

💡 HEAD response ends after headers; OPTIONS response ends after allowed methods headers.

Variable Tracker

Variable	Start	After OPTIONS	After HEAD	Final
Request Method	None	OPTIONS	HEAD	HEAD
Response Headers	None	Allow: GET, POST, HEAD, OPTIONS	Resource headers only	Resource headers only
Response Body	None	None	None	None

Key Moments - 2 Insights

Why does the HEAD response have no body even though the resource exists?

Because HEAD returns only headers without the body, as shown in execution_table step 2 and 3.

What information does the OPTIONS method provide to the client?

OPTIONS returns the allowed HTTP methods for the resource in the Allow header, as seen in execution_table step 1.

Visual Quiz - 3 Questions

Look at the execution_table, what does the server send back in response to the OPTIONS request?

A Only status code 200 OK

B Full resource body

C Headers listing allowed methods

D No response

💡 Hint

Check execution_table row 1 under Response Content

At which step does the server send headers without a body?

A Step 1

B Step 2

C Step 3

D No step sends headers only

💡 Hint

Look at execution_table rows 2 and 3 for Response Content

If the client wants to know if POST is allowed, which method should it use according to the execution flow?

A OPTIONS

B HEAD

C GET

D PUT

💡 Hint

Refer to concept_flow and execution_table step 1 about allowed methods

Concept Snapshot

HEAD and OPTIONS methods:
- OPTIONS asks server which methods are allowed
- Server responds with Allow header listing methods
- HEAD requests headers only, no body
- Useful for checking resource metadata or capabilities
- HEAD response matches GET headers but no content

Full Transcript

This visual execution shows how the HEAD and OPTIONS HTTP methods work. First, the client sends an OPTIONS request to the server asking which HTTP methods are allowed on a resource. The server responds with headers including an Allow header listing methods like GET, POST, HEAD, OPTIONS. Next, the client sends a HEAD request to get only the headers of the resource without the body. The server responds with headers but no content body. This helps clients check resource metadata or capabilities without downloading the full content. The execution table traces each step, showing request method, server action, and response content. The variable tracker shows how request method and response headers change. Key moments clarify why HEAD has no body and what OPTIONS returns. The quiz tests understanding of these steps. The snapshot summarizes the key points for quick review.