Domain table (name-to-address table)

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. What does a domain table pair together?

A Each domain name with an IP address

B Each IP address with a MAC address

2. A DNS server gets a request for shop.example.com. What does it do first?

A Looks the name up in its domain table

B Sends the request straight to the router's MAC address

3. The table has the row: school.edu.au | 203.0.113.8. What is 203.0.113.8?

A The password for school.edu.au

B The IP address for school.edu.au

4. A student types a domain name that is NOT in the DNS server's domain table. What is the most likely result?

A The page will not load because no address is found

B The page loads faster from a backup table

5. The table lists bank.com.au with the IP address of a scammer's server. What happens when users visit bank.com.au?

A They still reach the real bank safely

B They are sent to the wrong server

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1shop.example.com → 203.0.113.15		AA domain table entry that pairs the name shop.example.com with the IP address 203.0.113.15
2lookup("school.edu.au") → not found		BThe table entry has an invalid IP address because 300 is above 255. The name can never be matched to a real device.
3A DNS server reads a domain table to find the IP address that matches a name		CThe table holds the wrong IP address for this name, so users who type the correct name land on a different server.
4A wrong entry can redirect users to a fake site (pharming)		DThe domain table has no entry for this name, so the DNS server cannot give back an IP address
5games.example.com → 203.0.113.300		Ebank.example.com → 192.0.2.99 (attacker's server)
6news.example.com → 192.0.2.50 (should be 203.0.113.8)		Ftable["mail.example.com"] = "198.51.100.7"

Definitions

domain table

Fill in the Blanks

Complete each line of code by filling in the missing parts.

school.edu.au 203.0.113.5 lookup school.edu.au -> ___________

shop.com.au 198.51.100.7 lookup news.com.au -> _________

bank.com.au 203.0.113.66 real bank IP: 203.0.113.10 Users are sent to the _____ server

games.com.au 192.0.2.44 mail.com.au 192.0.2.45 lookup ___________ -> 192.0.2.45

A DNS server looks up a name in the ____________ to find its IP address

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A school.edu -> 203.0.113.310

B shop.com.au -> 198.51.100.7

C news.com -> 192.0.2.44

Question 2

A name ← 'shop.com.au'

B IF name is in the table

C SEND to the name typed

D ELSE

E SHOW 'not found'

Question 3

A bank.com.au -> 192.0.2.10

B mail.com.au -> 192.0.2.11

C game.com.au -> 192.0.2.12

D shop.com.au ->

Question 4

A # Real bank site: 192.0.2.10

B bank.com.au -> 198.51.100.99

C # Wrong entry = wrong site

Question 5

A table ← domain table

B ip ← table['192.0.2.50']

C OPEN ip

Answer Key

Domain table (name-to-address table)

Section A: Quick Questions

A — Each domain name with an IP address

A — Looks the name up in its domain table

B — The IP address for school.edu.au

A — The page will not load because no address is found

B — They are sent to the wrong server

Section B: Match the Pairs

shop.example.com → 203.0.113.15 → A domain table entry that pairs the name shop.example.com with the IP address 203.0.113.15

lookup("school.edu.au") → not found → The domain table has no entry for this name, so the DNS server cannot give back an IP address

A DNS server reads a domain table to find the IP address that matches a name → table["mail.example.com"] = "198.51.100.7"

A wrong entry can redirect users to a fake site (pharming) → bank.example.com → 192.0.2.99 (attacker's server)

games.example.com → 203.0.113.300 → The table entry has an invalid IP address because 300 is above 255. The name can never be matched to a real device.

news.example.com → 192.0.2.50 (should be 203.0.113.8) → The table holds the wrong IP address for this name, so users who type the correct name land on a different server.

Section C: Definitions

domain table — A list pairing each domain name with an IP address. A DNS server looks up a name in it. A missing or wrong entry sends users to the wrong place or nowhere.

Section D: Fill in the Blanks

school.edu.au  203.0.113.5
lookup school.edu.au -> 203.0.113.5

shop.com.au  198.51.100.7
lookup news.com.au -> NOT FOUND

bank.com.au  203.0.113.66
real bank IP: 203.0.113.10
Users are sent to the wrong server

games.com.au  192.0.2.44
mail.com.au  192.0.2.45
lookup mail.com.au -> 192.0.2.45

A DNS server looks up a name in the
domain table to find its IP address

Section E: Spot the Error

A — An IPv4 number can only go up to 255, so 310 is not a valid address. The entry should be 203.0.113.10, otherwise the DNS server has no real address to return.

C — Computers send data to an IP address, not a name. When an entry is found, the request must go to the stored address from the table.

D — This entry has a name but no IP address, so it is effectively a missing entry. The lookup for shop.com.au would lead nowhere. It should be shop.com.au -> 192.0.2.13.

B — The entry does not match the real bank address of 192.0.2.10. A wrong entry like this redirects users to another server, which is how pharming works.

B — A domain table is searched by domain name, not by IP address. The lookup should use the name 'cafe.com.au' to get the address.