Undergraduate is a software major, but because of family reasons, I introduced to a communication company and got in touch with IE. I feel that it may be very good if I can pass the exam. Related?

In a tcp connection, if only the client side has been uploading files, and the other side's server will send a confirmation ack packet after receiving the packet, does the data content of this packet have a length?

Forward proxy and reverse proxy (application load balancing, some NG reverse proxy) can be understood as a man-in-the-middle mode. At the same time, both ends establish a TCP connection, and then the man-in-the-middle performs TCP connection between the two ends.

If the client is connected to port 80 of the server, all data is sent to port 80. At this time, the port in tcp protocol is 80. However, the server only listens on port 80, and then uses a new socket to communicate with the client. The new socket port is reassigned.

Home Internet access is NAT, and Ping is not connected to other IP on the network segment (confirm online). What isolation technology is used?

How to ensure that the authentication information (AccessToken, etc.) sent by the client is not obtained or forged? Which encryption method would be better?

We know that the PDU of the application layer is a message, and finally becomes the bit stream of the physical layer to propagate, so what is the relationship between the message format of a protocol and the body of this message? What is the role of understanding the message format of a protocol?

Where are the TCP connection-oriented features?

Recently, I was reading the article about TCP connection. I have a doubt. I hope you can help. Where is the connection-oriented feature of TCP? Because the three-way handshake of TCP seems to the router to forward three ordinary packets, the router will not reserve bandwidth resources for this session. Where is the "connection" feature of TCP?

First, let ’s make a statement. The default route and default route (Default Route) of all devices on the earth are “0.0.0.0”. The device here refers to any host, virtual host, router, switch, firewall. Therefore, there is no problem if the default route of the subject is "0.0.0.0".