The question is asking for the correct sequence of events when a browser requests a webpage from a remote server, given that the host has just been restarted.
The correct sequence is:
- DNS query: The client needs to resolve the server's domain name into an IP address to know where to send the request. This is accomplished using the Domain Name System (DNS).
- TCP SYN: Once the client has the server's IP address, it initiates a TCP connection with the server. This is done using a SYN (synchronize) packet, which is part of the TCP three-way handshake (SYN, SYN-ACK, ACK).
- HTTP GET request: Once the TCP connection is established, the client can send an HTTP GET request to the server to ask for the webpage.
So, option 3 (DNS query, TCP SYN, HTTP GET request) is the correct answer.