Application layer

Fifteen GATE-style questions on Phase 5, with a few that reach back into earlier phases.

1. MCQ · 1 mark

   Which statement about client-server is correct?

   1. The server starts each exchange.
   2. The client uses a well-known port.
   3. The server listens on a well-known port.
   4. Only UDP can be used.
2. NAT · 1 mark

   A TCP server has 40 open connections. Sockets in use by the server process?

   Write your answer before opening the key.

3. MCQ · 1 mark

   Which DNS record maps an alias to a canonical name?

   1. A
   2. CNAME
   3. MX
   4. NS
4. NAT · 1 mark

   Cold-cache iterative DNS: host↔local 2 ms, root 30 ms, TLD 20 ms, authoritative 10 ms. Lookup ms?

   Write your answer before opening the key.

5. MSQ · 1 mark

   Which are true?

   1. DNS normally uses UDP port 53.
   2. HTTP runs over TCP port 80.
   3. HTTP keeps per-client state on the server by default.
   4. Cookies let a server recognise a returning browser.
6. NAT · 2 marks

   Base + 7 small objects, RTT 20 ms, non-persistent serial. Total ms?

   Write your answer before opening the key.

7. NAT · 1 mark

   Base + 7 small objects, RTT 20 ms, persistent without pipelining. Total ms?

   Write your answer before opening the key.

8. NAT · 2 marks

   Base + 15 objects, RTT 10 ms, non-persistent, 5 parallel connections, DNS 20 ms. Total ms?

   Write your answer before opening the key.

9. MCQ · 1 mark

   HTTP status 301 means:

   1. OK
   2. Moved permanently
   3. Not modified
   4. Bad request
10. MCQ · 1 mark

    Which HTTP method returns headers only?

    1. GET
    2. HEAD
    3. PUT
    4. POST
11. MCQ · 2 marks

    Correct order for a freshly connected laptop opening a page:

    1. DNS, DHCP, ARP, TCP, HTTP
    2. DHCP, ARP, DNS, TCP, HTTP
    3. ARP, DHCP, TCP, DNS, HTTP
    4. DHCP, DNS, TCP, ARP, HTTP
12. NAT · 2 marks

    DNS 8 ms, RTT 32 ms, page transmission 10 ms, one TCP connection. Page fully received after (ms)?

    Write your answer before opening the key.

13. MCQ · 1 mark

    Which server returns the final A record for www.example.com?

    1. Root
    2. .com TLD
    3. Authoritative for example.com
    4. Any router
14. MSQ · 1 mark

    Which change hop by hop on the way to the web server?

    1. Source and destination MAC addresses
    2. The frame's CRC
    3. The destination IP address
    4. The IP TTL
15. NAT · 1 mark

    Persistent pipelined HTTP: base + 20 small objects, RTT 15 ms. Total ms (DNS ignored)?

    Write your answer before opening the key.