How a name becomes an address

Computing · Networks & Security · ages 19-20

Name ______________________ Date ____________

Where does the resolution walk start?
- At your printer
- At the root
- At the old server
What does name resolution translate?
- Names into addresses
- Files into folders
- Passwords into names
What does the time to live set?
- The length of the name
- The speed of the network
- How long a cached answer may be reused
A record lifetime is one hour. When does the resolver ask again?
- After one second
- After one hour
- Never again
The com servers reply with the example servers. What happens next?
- The lookup asks the example servers
- The lookup stops with no answer
- The root address changes
Right after an address change, every user sees the new server at once.
Circle one: True False
Caching with lifetimes is what keeps repeated lookups fast.
Circle one: True False
A site moved servers, but you still see the old pages hours later. What best explains it?
- Your screen is too dim
- A stale cached answer is still within its lifetime
- The root forgot all names

Answer key

For grown-ups. Fold this page away before handing over the rest.

At the root · The walk goes from the root down the hierarchy.
Names into addresses · People remember names, machines route to addresses.
How long a cached answer may be reused · The lifetime tells the resolver how long the copy stays valid.
After one hour · The resolver reuses the copy and reasks once it expires.
The lookup asks the example servers · Each level hands the lookup one step further down.
False · Cached copies still point at the old server until they expire.
True · Reuse avoids walking the hierarchy for every single lookup.
A stale cached answer is still within its lifetime · A stale copy looks exactly like the old site until expiry.