Troubleshooting

Question 1

Which two commands would be used to troubleshoot high memory usage for a process? (Choose two)

A. router#show memory allocating-process table
B. router#show memory summary
C. router#show memory dead
D. router#show memory events
E. router#show memory processor statistics

Answer: A B

The “show memory allocating-process table” command displays statistics on allocated memory with corresponding allocating processes. This command can be also used to find out memory leaks. A memory leak occurs when a process requests or allocates memory and then forgets to free (de-allocate) the memory when it is finished that task.

Note: In fact the correct command should be “show memory allocating-process totals” (not “table”)

The “show memory summary” command displays a summary of all memory pools and memory usage per Alloc PC (address of the system call that allocated the block). An example of the output of this command is shown below:

Legend:

+ Total: the total amount of memory available after the system image loads and builds its data structures.
+ Used: the amount of memory currently allocated.
+ Free: the amount of memory currently free.
+ Lowest: the lowest amount of free memory recorded by the router since it was last booted.
+ Largest: the largest free memory block currently available.

Note: The show memory allocating-process totals command contains the same information as the first three lines of the show memory summary command.

An example of a high memory usage problem is large amount of free memory, but a small value in the “Lowest” column. In this case, a normal or abnormal event (for example, a large routing instability) causes the router to use an unusually large amount of processor memory for a short period of time, during which the memory has run out.

The show memory dead command is only used to view the memory allocated to a process which has terminated. The memory allocated to this process is reclaimed by the kernel and returned to the memory pool by the router itself when required. This is the way IOS handles memory. A memory block is considered as dead if the process which created the block exits (no longer running).

The command show memory events does not exist.

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/configfun/command/reference/ffun_r/frf013.html and http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-software-releases-121-mainline/6507-mallocfail.html

Question 2

A network engineer finds that a core router has crashed without warning. In this situation, which feature can the engineer use to create a crash collection?

A. secure copy protocol
B. core dumps
C. warm reloads
D. SNMP
E. NetFlow

Answer: B

A core dump is a file containing a process’s address space (memory) when the process terminates unexpectedly to identify the cause of the crash

Question 3

A network engineer is investigating the cause of a service disruption on a network segment and executes the debug condition interface fastethernet f0/0 command. In which situation is the debugging output generated?

A. when packets on the interface are received and the interface is operational
B. when packets on the interface are received and logging buffered is enabled
C. when packets on the interface are received and forwarded to a configured syslog server
D. when packets on the interface are received and the interface is shut down

Answer: A

Question 4

Various employees in the same department report to the network engineer about slowness in the network connectivity to the Internet. They are also having latency issues communicating to the network drives of various departments. Upon monitoring, the engineer finds traffic flood in the network. Which option is the problem?

A. network outage
B. network switching loop
C. router configuration issue
D. wrong proxy configured

Answer: B