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1st LVS Trivia Quiz, Jul 2000
To coincide with Wensong's talk at the Ottawa Linux Symposium 19-22 Jul 2000.
(Originally this was prepared for an LVS get together at Ottawa.
Only Wesong, Lars, Ratz and myself are going, so I'm posting
this to the mailing list while I'm away.
Wed Jul 18: we still haven't heard if Wensong got his
visa in Beijing to go. Good luck Wensong - Joe)
Disclaimer: All questions have been painstakingly researched.
The answers have not and will be posted after I return from Ottawa.
(some answers are in the "it depends" category. All correct answers
are acceptable). Alternate answers and flames from sore losers will
be hotly disputed on the mailing list after the official answers are posted.
Questions apply to the state of the LVS art at the end of Jun 2000.
Rules: Mark all answers that are correct
Score: 1 point for every correct answer or factoid.
Competition Divisions:
You can do this
1. from memory only
2. using any means at your disposal.
People using external information are required to drink 1 free beer
for every piece of help, before going to the next question.
Warning: This quiz may contain references to violence, sex, incitement
to illegally overthrow the goverment, foul language and bad grammar.
Then on the other hand it may not. You have been warned.
Personalities Category
1. Wensong lives in Changsha, China where he's
a. an academic at the National Laboratory for Parallel &
Distributed Processing
b. a student
c. unemployable
2. Who is "hidden"?
3. According to an unofficial count of the postings to the mailing list,
the most prolific posters are all born in the one country.
a. What's the country
b. Who are these blabbermouths?
4. What is Horms real name?
5 The machine that hosts the LVS primary website (www.linuxvirtualserver.org)
and mailing list
a. is in what country?
b. is provided by which LVS person?
Total World Domination Category
1. Name commercial products based on LVS code.
Heroics Category
1 point for each of the following
1. Set up a working LVS by any method.
2. Set up a working LVS completely from the command line.
3. Posted to the mailing list (1 point each)
a. anything at all
b. something useful
c. nothing because there is too much noise there already.
4. Have earned money for LVS work.
Lifestyle Questions
1. Have you ever programmed through to sunrise, because you couldn't
stop?
2. What is the normal number of ball point pens (biros (R)) that you
can put into a plastic pocket protector in a standard business shirt,
if you take your calculator out?
3. What are the advantages of no-iron shirts?
4. How many females have posted to the mailing list?
a. 0
b. 1-100
c. many
Techical Questions
1. How many penguins are in the LVS logo?
2. LVS has 3 distinct methods of getting a packet from the director
to the realservers, VS-NAT, VS-DR, VS-TUN.
a. which put the most load on the director
b. which have the lowest latency
3. Which of these pieces of hardware/software/companies are/make an L4 switch
a. F5
b. cisco
c. mon
d. BIG/ip
e. Matterhorn
f. Alteon
g. Redwood
h. Kudzu
i. lvs
j. SGI
k. ldirectord
4. Does LVS work on non-Intel Linux directors (if yes, which hardware is
known to work)
a. yes
b. no
5. Does LVS look inside the ethernet frames (or equivalent for other transport)
or does it look at the contents (data) of the packet before deciding
what to do with it.
a. ethernet frame
b. data
6. Can a VS-DR LVS use realservers running
a. NT
b. other non-linux unices
7. Does the "arp problem" affect
a. VS-NAT
b. VS-DR
c. VS-TUN
8. Under Linux, hidden interfaces may be established that will not
be advertised via ARP, whether directly connected or otherwise.
One method of avoiding the ARP problem with VS-DR and VS-TUN is
to make the interface with the VIP on which host(s) hidden:
a. the director
b. the realservers
c. all machines in the LVS
9. What can you do to handle the "arp problem" on an LVS running
2.2.x kernels (1 point for each method).
10. A VS-DR LVS with identical realservers and unweighted round robin
scheduling for the service telnet, is setup with the VIP on ethernet
devices. _All_ devices with the VIP reply to arp requests.
You connect to the LVS'ed service telnet many times in succession from
a client connected directly to the director and you observe which realserver
you connect to.
Which of these are possible:
a. you will connect to each realserver in the order listed by ipvsadm
(ie the LVS works perfectly)
b. you will connect to each realserver in random order
c. you will connect to a subset of the realservers in random order
d. you will always connect to the same realserver
e. the telnet connect request will hang.
11. A VS-DR LVS can be made to operate if the VIP is on
a. both the director and the realservers
b. the director only
c. the realservers only
d. none of the machines
12. You set up a demonstration LVS using some generic Linux boxes on hand.
The LVS handles telnet using round robin scheduling on 2 realservers,
but when you attempt to connect, you get "connection refused".
What could be wrong?
13. You fix this problem and next time the connection attempt hangs (forever).
What is likely wrong if the LVS is
a. VS-NAT
b. VS-DR
14. You fix this problem and and instead of connecting immediately,
the connection hangs for a while and then connects. On checking you
find that connecting to the realserver directly completes immediately.
What's wrong?
15. Your pointy haired boss is beginning to think you are crazy and wants to
buy the TurboLinux Cluster Server, but you doggedly start again and setup
a VS-DR LVS from scratch.
You get a gratifying immediate connection to one of the realservers. However
after a few minutes, you realise that you're connecting to the same realserver
every time, rather than alternating between the two realservers. What is wrong?
16. In failover setups where another director can replace a failed director,
during failover, the connection between the client and realserver is
a. maintained
b. dropped
c. hangs
17. What will the client in the previous question see on director failover
if the connection is
a. idle telnet
b. active ftp doing a file transfer
c. idle http, the browser reloads just after the failover completes.
d. http and is downloading a page at the time the director fails.
18. VS-DR has a different path for packets coming from the client and for
those returning. The result of this is that services like ftp, which have
large reply packets and small request packets, have
a. higher maximum throughput
b. the same maximum thoughtput
c. lower maximum througput
at the director than services like lpd, which have large request packets
and small replies.
19. An LVS can recognise/use the fwmark (firewall mark) on a packet.
The fwmark is put on the packet by the
a. client
b. routers on the internet
c. router/firewall just outside the director
d. director
e. realserver
20. The fwmark is recognised/used by the
a. client
b. routers on the internet
c. router/firewall just outside the director
d. director
e. realserver
21. The fwmark allows
a. the director not to have a VIP
b. the director to accept LVS requests destined for a
subnet of addresses
c. security precautions to block DoS attacks
22. A VS-DR realserver is doing an ftp transfer with a client which goes
down during the transfer. A router near the client sends back a
"host unreachable" icmp packet.
a. What LVS machine handles this packet?
b. What does this machine do with the icmp packet
(eg accept, drop, reject)?
c. What is the LVS's response to the icmp packet?
(C) Joseph Mack and the LinuxVirtualServer Project 2000.
May be used anywhere with acknowlegement.
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Joseph Mack mack@xxxxxxxxxxx
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