Fill in lab01 portfolio summary

lab-01-trace-request/portfolio-summary.md

@@ -14,10 +14,10 @@ In this lab, I worked with a simple virtual Linux network and used networking to
 
 In one or two sentences, explain how the client moves from `web.minicorp.test` to its next-hop device.
 
-> Replace this line with your explanation.
+> The client resolves from web.minicorp.test to an IP address via DNS, and then it checks the destination IP against its routing table to find the next-hop IP. After that, it uses ARP to resolve the next-hop IP to a MAC address, and it sends the frame to that MAC address over the local network. 
 
 ## Key takeaway
 
 Explain why the client needs both an IP address and a link-layer address when sending traffic to the next hop.
 
-> Replace this line with your explanation.
+> The IP address identifies the final destination and lets the packet be routed accross multipule networks, while the MAC address is only for the local network as it tells the switch which NIC to deliver the frame to. The client needs both the IP and the MAC because the IP address alone cannot get a frame to move across the wire, and the MAC address by itself cannot get the packet accross multipule different networks. I like to think of it like this: The IP address is the mailing address on an envelope. It represents the final destination, for example: 12345 El Monte Rd, Los Altos Hills, CA 94022-4504. When the letter goes through the USPS, it travels from local carriers, regional sorting facilities, state sorting facilites, thrid party carrier networks, etc.. At each leg of that journey there is a barcode that says "send this from UPS San Francisco sorting to UPS Los Angeles sorting," and it gets replaced at the next sorting facility with something like "send this from UPS Los Angeles sorting to USPS Torrance post office." That is the MAC address, it identifies the next physical hand-off. Without the MAC, only the final destination would be known but not how to route it there (USPS, FedEx, UPS, etc.). Without the address it would known where to route the mail but not any further than one hop, at UPS Los Angeles they would only know to send it to USPS Torrance, but not if it will be on a local delivery route next or be loaded onto a long-distance mail truck.