GATE CS 2024 Set 1 — Question 16

MCQ+1 / -0.33EasyDNSApplication LayerComputer NetworksHTTP & HTTPSTCP HandshakeTransport Layer

Computer Networks → Application Layer → DNS

Last updated 20 August 2026

Question

A user starts browsing a webpage hosted at a remote server. The browser opens a single TCP connection to fetch the entire webpage from the server. The webpage consists of a top-level index page with multiple embedded image objects. Assume that all caches (e.g., DNS cache, browser cache) are all initially empty. The following packets leave the user’s computer in some order.

(i) HTTP GET request for the index page
(ii) DNS request to resolve the web server’s name to its IP address
(iii) HTTP GET request for an image object
(iv) TCP SYN to open a connection to the web server

Which one of the following is the CORRECT chronological order (earliest in time to latest) of the packets leaving the computer ?

(iv), (ii), (iii), (i)

(ii), (iv), (iii), (i)

(ii), (iv), (i), (iii)

(iv), (ii), (i), (iii)

Correct answer

Solution

To fetch a webpage when all caches are empty, the following sequence of events must occur:

1.DNS Resolution (ii): The browser first needs to know the IP address of the remote server. It sends a DNS request to resolve the hostname.

2.TCP Connection Establishment (iv): Once the IP address is obtained, the browser must establish a TCP connection with the server. This begins with a TCP SYN packet.

3.HTTP Request for Index Page (i): After the TCP connection is established, the browser sends an HTTP GET request to fetch the main index page of the website.

4.HTTP Request for Embedded Objects (iii): The browser receives and parses the index page. Upon discovering embedded objects (like images), it sends subsequent HTTP GET requests to fetch those specific objects.

Therefore, the correct chronological order is (ii) → (iv) → (i) → (iii), which matches option (C).

GATE CS 2024 Set 1 — Question 16

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