Question

Starting at the customer's CPE and ending with a remote web server such as the New York Times webserver, describe the Internet Architecture which the path of a typical packet would follow.

Answer 1

Description of the Internet Architecture path a typical packet follows starting at the customer's Customer Premises Equipment (CPE) such as his/her Internet web browser application software, desktop or laptop, router or modem, and ending with a remote web server such as the New York Times webserver:

The Internet is the backbone of the Web, the technical infrastructure responsible for the Web to work. When a user types in the website address of the New York Times web server in the address of a web browser and presses enter key, it in general tries to reach the below website address of theirs.

https://www.nytimes.com

* In general, the data packet goes from the web browser application software to the user's router and to his local modem, then to the ISP's router, then to the Internet (a network of networks), then to the ISP's DNS servers, finally to the webserver. The processed data packet travels all the way back to the user's computer following the reverse order of the exact same path.
* In detail, the user's web browser first checks the local on his/her computer cache for a DNS record to find the corresponding IP address of www.nytimes.com website. It checks the browser cache. Then, the browser checks the OS cache. It then checks the router cache for the same. Finally, it checks the ISP cache. ISPs maintain their own DNS servers. DNS is a database maintaining and mapping the website names or domain names (URLs) to their corresponding unique IP addresses they link to.

* In case, the requested URL (Uniform Resource Locator) is not found in the cache, his/her ISP’s DNS server triggers initiation of a DNS query looking for an IP address of the webserver hosting www.nytimes.com.

The user computer needs the IP address of www.nytimes.com. The DNS query searches for multiple DNS servers on the Internet until it finds the IP address for www.nytimes.com through recursive search through repeated search from DNS server to another DNS server until it finds the IP address for the webserver. ISP's DNS server or DNS recursor to looking for the IP address of the webserver for the domain name asking other DNS servers on the Internet. The other DNS servers are name servers as they perform a DNS search on the domain name. In the process, the request goes from the DNS recursor to the root name server. The root name server redirects it to .com (top-level domains) domain name server. .com name server redirects it to nytimes.com name server. The nytimes.com name server would find the matching IP address for www.nytimes.com in its DNS records and returns it to the ISP's DNS recursor which then sends it back to the user's web browser.

* The web browser then initiates a TCP connection with the server.
* The browser then sends an HTTP request to the webserver.
* The web server then handles the request, processes it, and responds with the page result send the user computer the HTTP response with the requested page information.
* The browser displays the HTML content of the webpage available on the website at the above-specified domain name.

Data is transmitted from the user to a desired remote or destination web server over the Internet through packets. All devices, machines, servers, routers, switches, other network devices, hosts, desktops, laptops, mobile devices, printers, etc, have their own IP addresses. A user's desktop or laptop in general, is connected and sends the data through packets from a web broser software such as Google Chrome, Mozilla Firefox, etc., to a router which is connected to a modem (MOdulator and DEModulator), the setup may even have a switch (managed or unmanaged), these are then in turn connected to the user's ISP (Internet Service Provder), which is connected to the backbone of the network or the Internet, the root servers and DNS (Domain Name System) servers are also conneted in the backbone of this network, and at the other end (logically and even physically) are the web servers connected.

All the routers connected to the Internet keep and follow routing tables that contain the information used to get packets to their destinations. These routers are packet switches. Routers connected between different networks control the flow of traffic and route packets amongst themselves and also keep their sub-networks and the IP addresses they use. These router could be wired or wireless routers. Sometimes both, the router and a switch could be in one single equipment. The Internet connection lines could either cables such as copper twisted pair or fiber optics; or wireless such as satellite communication.

Internet Architecture works ccordance with the Internet Protocol (IP), the Transport Control Protocol (TCP) and other protocols. The data packet thus, travels from the user's computer to his/her Modem, then to the Public Telephone Network (PTN), to the Modem Pool, which is connected to the user's ISP Port Server connected to a router which is inturn connected to the ISP backbone. This is only half part of the Internet architecture.

Each of the packets carry upto 1,500 bytes with a header and a footer, and letting the computers and other devices know what kind of data is in the packet, the source and the destination, and how it fits together with other data. While the data packet is being transmitted on the Internet, different packets of the message do not follow the same path. The source computer disassembles data packets of a message to transmit them, while the destination (receiver) computer or web server assembles the data packets to form the original message the source or the user computer had sent. However, whenever there is a congestion or any other issues on the Internet specifically on a certain path, packets take a different route to go through. In case a packet does not reach its destination, the computer or the server supposed to receive the data determinse the packet missing referencing the other packets based on a sequence and order mantained, asking the source to resend the data packet creating redundancy.