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Question 43

User report that they can no longer able to process transactions with the online ordering application, and the logging dashboard is displaying these messages.

Fri Jan 10 19:37:31.123 EST 2020 [FRONTEND] INFO: Incoming request to add item to cart from user 45834534858

Fri Jan 10 19:37:31.247 EST 2020 [BACKEND] INFO: Attempting to add item to cart

Fri Jan 10 19:37:31.250 EST 2020 [BACKEND] ERROR: Failed to add item: MYSQLDB ERROR: Connection refused

What is causing the problem seen in these log messages?

    Correct Answer: A

    The error message 'Connection refused' typically indicates that the requested service is not available at the specified port. This can happen when the database server is not running or has crashed. MySQLDB ERROR: Connection refused suggests the database server is either down or unreachable, aligning with the scenario where the database server container has crashed.

Discussion
romanknetOption: A

A The message 'Connection Refused' has two main causes: Nothing is listening on the IP:Port you are trying to connect to. The port is blocked by a firewall. Source - https://serverfault.com/questions/725262/what-causes-the-connection-refused-message

blezzzoOption: A

I'll go with A here. Explanation If you get the error message Can't connect to MySQL server on some_hostname, you can try the following things to find out what the problem is: Check if the server is up by doing telnet your-host-name tcp-ip-port-number and press Enter a couple of times. If there is a MySQL server running on this port you should get a response that includes the version number of the running MySQL server. If you get an error like telnet: Unable to connect to remote host: Connection refused, there is no server running on the given port.

eggsterminatorOption: C

C Its not A. Connection refused means that the server was able to respond back to you. If you try to open a TCP connection to another host and see the error "Connection refused," it means that You sent a TCP SYN packet to the other host. Then you received a TCP RST packet in reply. RST is a bit on the TCP packet which indicates that the connection should be reset. Usually it means that the other host has received your connection attempt and is actively refusing your TCP connection, but sometimes an intervening firewall may block your TCP SYN packet and send a TCP RST back to you.

routeswitchOption: C

IF THE CONTAINER HAS CRASHED THE ERROR MESSAGE WOULD NOT SAY REFUSED

xXXDarkWizardXXxOption: B

B. If the system is down you get request timeout, not 'Connection Refused'

after_eight

If a container crashs, the system is still up and has no more process which listens the port, you will have the Connection Refused error. I would go for A

FR99Option: A

A go with 'A'

Nizrim

Who in the right mind would put DB server into container? Answer is C

Lala26

The error message is "Connection refused" not "Not authorized" or similar.

djv_exam

:) this is being very much debated this days, a lot of people are experimenting and defending the usage of containers in DB

duracell

that's why you should not run it like this... it crashed ;)

razvan999Option: C

Connection refused implies that the DB is UP, like a 403 error code, not like the 500 range(A)

razvan999

Actually, is A: https://googlecloudcommunity.com/gc/Databases/ERROR-SQLSTATE-HY000-2002-Connection-refused/m-p/631473#:~:text=This%20can%20be%20caused%20by,access%20to%20the%20database%20server.

VincentVegaOption: A

A. The database server container has crashed. and C. The backend is not authorized to commit to the database. Are correct answers (and B also can be correct at certain circumstate ) If You troubleshoot Connection refused error - first step check the configuration and credentials But also important - is it works before? Yes it works fine before - "User report that they can no longer able" So question - what happened? And for this perspective A is more preferable. And finally from DevCore study guide 350-901 p 34 : If a log indicated “Connection refused” or “Connection timeout,” quite often Linux admins would blame the network (which could be true), but in reality (or highly likely), some service on a server did not start or some container crashed. Another possible reason could be a server overload.

gregemilOption: B

B Not A because it would be a timeout and not refusal. Not C because it's connection that is refused and not transaction B is caused either by some limit on tcp concurrent connections or a db level limit.

examSharkOption: A

A. The database server container has crashed. If the database server has crashed or is not running, any attempts to connect to it would be refused, which aligns with the "Connection refused" error message. B. The backend process is overwhelmed with too many transactions. If the backend were simply overwhelmed, you'd expect to see timeout errors or performance-related messages, not a "Connection refused" error. C. The backend is not authorized to commit to the database. Authorization issues typically result in error messages about invalid credentials or permissions, not connection refusals. D. The user is not authorized to add the item to their cart. This would typically generate an error message about authorization or access control, not a connection issue. Based on the error message "Connection refused," the most likely cause is A. The database server container has crashed. This would result in refusal of connection attempts from the backend service.

FedesaruchoOption: A

A has more sense, DB is not taking connections

doble_hOption: A

A common reason for this error is that the database server is down or not responding, which could be due to a crash or some issue with the database server container.

JCGOOption: C

It is C. Not A, since MySql will not reply in case of container failure. Not B, because this will be “Too many connections” error Not D, because this will be “Access denied for ..."

TeringzooiOption: A

A seems to be suitable.

bboycoiOption: A

I agree with A, but I really hate this kind of question

__al__Option: A

Strange question... the least terrible option is A indeed.