Intrvw

= AMZN Networking =

Round 1
Directions? Session Ticket OSPC Stapling TC Flag
 * BGP Route manupulation
 * Anycast
 * Linux check WSF
 * SSL speed up at LB level:
 * Cookie Uses
 * Google BBR - congestion control algorithm
 * DNS check if reply is spoofed or not?
 * How does DNS client knows when to switch to TCP?

Round 2

 * Experience with diffcult customer
 * Learnt from feedback

RDP, VNC (Teamviewer, Webex for PC) RDP Port no TCP port 3389 and UDP port 3389
 * Windows
 * How to remotely access Windows server?
 * Page file
 * Service
 * Service fails, how to check logs? (Event logs viewer)


 * Linux
 * Kernel
 * Inode
 * Check CPU, Memory, HDD info?
 * Check Load Average? What is the output?(1,5,15 min avrg), what does it mean?
 * Check Clients we are connected to? netstat -ant -> Foreign Address
 * ifconfig -a - eth0:1 - What does :1 mean? (vlan)
 * Check file in use by which process? lsof
 * Runlevels
 * Check DNS config? /etc/resolv.conf & interface config
 * Iptables?

curl -v http://google.com telnet nc ipconfig netstat traceroute top ps free df dh
 * Networking
 * NAT
 * How does Traceroute works?
 * Request & response headers
 * Commands used in daily troubleshooting

[PC]-[Website] 1st attempt - 404 2nd attempt - 200 3rd attempt - 404 4th attempt - 200 LB having 2 servers, one is not having app installed, check logs & disable it.
 * Scenario

Round 4 - Architecture
- Avi SE scaling, use 3 node cluster for controller - Use 2 AZs - How DB will sync - GSLB usage - geodb Networking - how persistence will work - Storage redundancy - Storage slow, use SSD - Pics load slowly in Japan
 * Explain case you have worked - Voip CB Repro
 * Design a Ecommerse website with full redundancy, explain protocols used:

Round 5 - Linux
- Stop  (my answers) - Start - Running - Sleeping ==> Interupptable waiting/ uninterruptable waiting -> Explain each - Killed - Zombie
 * Boot process in detail
 * What is kernel? How does it communicate with HW/User? System calls
 * Name the various System calls
 * What is initrd ? What it contains/does ? (drivers to load disk,etc)
 * Runlevels
 * Upstart/Systemd
 * What is Swap?
 * How to find swap usage?
 * How to find if a file is moving from RAM to SWAP? iotop(process wise usage) & iostat(part wise usage)
 * How to check processes using most CPU/How to check CPU usage per core?
 * Process States:

- Format - Partition - Mount
 * Type of File systems - FAT32/ExFAT, NTFS, EXT3, EXT4
 * How to use a brand new disk in Linux machine

6 -> user     - Read/Write 4 -> group  - Read 0 -> Others - None
 * What are permissions -> 640?

- Buffer/Cache field? - Swap field?
 * How to check Memory usage - top//free -m // cat /proc/meminfo

df -h => check free disk space df -i => Free inodes check
 * How to troubleshoot if a file stopped coping in between saying no disk space, but disk space is there.


 * What is inode? How can they get full(mail server; large no of empty files)?

Round 6 - Networking
curl -I,  telnet,    nc,    ping
 * Design a website for 500 Employees - use 2 AZs?
 * Troubleshoot a website not reachable?

dig @42.2.2 google.com
 * How to check if DNS is working or not?


 * Check packet captures using tcpdump.
 * Explain DNS resolution in Full details.
 * Troubleshooting a slow website:

Top --> CPU, Memory,  Process usages, Load avg df -h --> Disk usage free -m cat /proc/meminfo netstat -ant cpu ==> 0 "us" user space top -o %CPU

Hello DBD LSR LSU [LSAa] LSAck
 * Explain TCP Window? How it can be full
 * OSPF vs BGP? why not use OSPF for Internet instead of BGP?
 * OSPF packet types?

Need to know about the type of attack Syn Flood attack can be mitigate by using Syn-Cookie
 * What is Area 0 in OSPF?
 * BGP Attributes
 * BGP getting more traffic from one ISP than other? How to balance that?
 * What is DDOS attack? How to mitigate it?
 * What is Syn-Cookie used for?

Round 7

 * Repro Attempt
 * Something not done within committed time
 * Something done differently from a colleague
 * Something you have done apart from regular work
 * Tough Feedback received; What you did about it.

= AMZN DMS = Tell me something where you did something extra during a case/your job Tell me something where you learned something during a case/your job Where do you store your code(Github)? How can some one other edit code? How DNS works? Explain in detail. DNS traffic Flow? Search local cache > hosts file > DNS server What is VoIP? How SIP works? Scenario: [LB]--[srv1][srv2][srv3]srv4] Srv3 is slow, latency, how to troubleshoot? top, free -h, df -h How to check traffic requests coming per second? netstat -s, ss -s, tcpdump
 * 1st Round Online Challenge
 * Telephonic Round

= Google =

Challenge
= CouchBase =

A page fault (sometimes called #PF, PF or hard fault) is a type of exception raised by computer hardware when a running program accesses a memory page that is not currently mapped by the memory management unit (MMU) into the virtual address space of a process.
 * OOM Killer
 * Page Fault

Create Static entry Increase Cache Time
 * Swap Memory
 * DNS Rate Limiting Troubleshoot

Check RTT for other traffic & DNS Specific traffic.
 * DNS latency in Server or Network Troubleshoot:

startTime : 12332121324 endTime : 21342313222 serviceName : abc status : 200
 * Print below logs:

startTime : 12332121324 endTime : 21342313222 serviceName : abc status : 200

startTime : 12332121324 endTime : 21342313222 serviceName : abc status : 200

startTime : 12332121324 endTime : 21342313222 serviceName : abc status : 200

startTime : 12332121324 endTime : 21342313222 serviceName : abc status : 200

f=open('text.txt','r') l=f.readlines
 * My Solution:

a=[]

for i in l: if ":" in i: a.append((i.strip('\n')).split(':'))

b=[] for i in range(len(a)): b.append(a[i][0])

b=set(b)

for i in b: print(i,end='')

for i in range(len(a)): if "startTime " in a[i]: print(a[i][1],a[i+1][1],a[i+2][1],a[i+3][1],end='') print('\n', end="")

= Juniper =

Is UDP Stateful How is UDP connectionless FTP types What is Frag Offset IKE v1 vs IKE v2