Week 1 worksheet — Foundations
| Name | Date |
|---|---|
1 — Two nodes, one cable
Predict. Are two computers and one cable enough to make a network? ☐ yes ☐ no
Why: __________
Observe.
| Value | |
|---|---|
| PC1 IP / MAC | |
| PC2 IP / MAC | |
| Ping, before addressing | |
| Ping, after addressing | |
Ping, with PC1 on /25 |
Explain. Why did the /25 break it?
2 — Client-server vs peer-to-peer
Predict. Between client-server and peer-to-peer, which is more vulnerable to in single node failure?
Observe.
| Client-server | Peer-to-peer | |
|---|---|---|
| Nodes with a listening socket | ||
| Conversations lost when H1 fails | ||
| Conversations lost when H2 fails |
Apply. What one command would you run on an unknown machine to tell you whether it is acting as a server and why?
3 — Where are the layers
Predict. How many different kinds of metadata does a request need to carry to retrieve a web page?
Can you name them?
Observe — the PDU table. (Referred back to in weeks 3, 4 and beyond. Keep it.)
| Wireshark layer | Layer # | Layer name | PDU name | Addresses here | Bytes |
|---|---|---|---|---|---|
| Ethernet II | |||||
| IPv4 | |||||
| TCP | |||||
| HTTP | |||||
| Data | — | — | — | — | |
| Total |
4 — Speak a protocol by hand
Predict. You mistype GET as GIT. Who notices? ☐ your computer ☐ the server ☐ neither
Observe.
| Attempt | Exact server response |
|---|---|
no Host: header |
|
| nonexistent file | |
GIT instead of GET |
|
| no HTTP version |
Explain. Your computer transmitted GIT without complaint. What does that tell you about where
a protocol is enforced?