fizzbuzz in ruby

#!/usr/bin/env ruby

(1..100).each do |num|
  three = (num % 3 == 0)
  five = (num % 5 == 0)
  print 'fizz' if three
  print 'buzz' if five
  print num if (!three and !five)
  puts
end

Interview: sysadmin

Command line tools

Which tools have you used in below categories? With which options? What do the options perform? (possible answers/options listed after category)

  * network tools

    * iftop: n, N, P
    * lsof: i, p, c, N, P
    * tcpdump: n, host, net, and, or
    * iptables: t, L, n, D
    * dig: txt, mx, a, cname
    * ping
    * traceroute/mtr

  * filesystem tools

    * df: h, a, s, T
    * du: s, h
    * fdisk: l
    * mkfs
    * find: exec, name, type
    * updatedb/locate

  * monitoring tools / process management

    * watch: d, n
    * ps: a, u, x, w
    * htop
    * vmstat: <seconds>
    * sa/sar
    * nice
    * smartctl
    * iostat: <seconds>, x, m


* Filesystems

  * Which are the types of filesystems: ext3, ext4, xfs, brtfs
  * What is an inode? How would you handle a "disk full" error related to inodes usage?


* Networking

  * What is port forwarding and how have you used it?
  * What is CIDR, show examples?
  * What is NAT? How have you used NAT technology?
  * What are the types of protocols? Explain their use. (tcp, udp, icmp)
  * Which hardware/software firewalls have you used? Explain.
  * Have you used VPN technology? Explain what was done and how you were involved.


* AWS

What is your experience with AWS? Detail/diagram projects.

Which AWS technologies have you used?

  * EC2

    * How have you managed AWS servers: API, web interface, command line tools?
    * Which types of instances have you used?
    * How many servers were you responsible for?
    * What is the difference between EBS and ephemeral storage? Pros/cons.

  * EBS

    * Which parameters does volume creation require?
    * What is a snapshot? How are redundant blocks stored for subsequent snapshots?

  * ELB

    * What is the "health check" used for? What are the parameters
    * Have you used SSL with ELB?
    * What are "listeners"?
    * Have you used ELB in conjunction with haproxy. Diagram.

  * VPC

    * How did you use VPC? Have you setup a AWS VPC from scratch?
    * Do you know what a "DHCP option set" is? How is it used?
    * Diagram what subnets were used, which were public, and which private.

  * SES

    * What is a "verified" email or domain in SES?

  * Route 53

    * Have you created a domain in Route 53?
    * Have you maintained DNS records with Route 53?
    * What does Route 53 offer that other DNS services do not?
    * How does Route 53 integrate with AWS ELB technology?

Monitoring

  * CloudWatch

    * How did you use CloudWatch to monitor server health and network use
    * Did you ever setup a CloudWatch email alert? Explain steps involved.

  * Zenoss

    * What are the tools you used in Zenoss
    * How large was the monitored infrastructure?
    * What is a Zenoss event?

  * On-call

    * Talk about your past on-call experiences, and one time handled a major issue
    * What are the available paging services, and which have you used?

Java

  * What experience do you have installing/supporting Java?
  * Explain how you performed JVM monitoring.
  * Tomcat
    * Have you ever supported Tomcat? What were the configurations you were responsible for?
    * What are the core Tomcat configuration files? Log files?
  * What is the Java Heap? How can this be set/modified, and what are the effects? Downsides?
  * What steps would you take to debug/resolve a "Out of Memory" JVM error?

Cassandra

  * Explain your experience with Cassandra. Versions?
  * How many nodes did you support? What percent of the data load was each node responsible for?
  * nodetool: what are the options, and what do they show/perform?
  * Explain how you built a ring from the ground up in the past
  * What steps did you take to monitor your Cassandra nodes?
  * What steps did you take for a node failure?
  * How did you find/get answers to questions you had on the Cassandra techonology?

In-memory page states and kscand

1. kscand task
1. periodically sweeps through all the pages in memory
2. notes "last access time"
1. was accessed?
1. increments page's age counter
2. wasn't accessed?
1. decrements page's age counter
3. age counter at zero
1. move page to inactive dirty state

In-memory page states

1. free
1. begin in this state
2. not being used
3. available for allocation, i.e. made active
2. active
1. allocated
2. actively in use
3. inactive dirty
1. has fallen into disuse
2. candidate for removal from main memory
4. inactive laundered
1. interim state
2. contents are being moved to disk
1. when disk I/O operation complete
1. moved to the inactive clean state
2. if, during the disk operation, the page is accessed
1. moved back into the active state
5. inactive clean
1. laundering succeeded, i.e. contents in sync with copy on disk
2. may be 
1. deallocated
2. overwritten

Taken: http://www.redhat.com/magazine/001nov04/features/vm/