Gary Allison's Leadership Blog

Cloud Computing11 Dec 2017 05:54 am
Time to dedicate to this blog has been little and far between, but I resolve to make it more frequent this coming year. Just completed my second AWS certification and thought I’d write a few notes here to hopefully help others.  The blueprint I have found successful:
  1. First, I would heavily recommend training courses as prep for the exam. It is a great foundation to start from. The courses are exceptionally well done, very affordable, and give great exam tips.  These were recommended to me by at the 2016 reinvent and it was a great suggestion. Just do it.
  2. There’s no substitute for experience.  I’m convinced if not for my years of experience with TCP/IP, software development, network configuration, etc, I would not have passed the exams.  While I don’t have deep experience developing on AWS, my background with AWS, years of experience, plus the prep was a winning combination.
  3. Read the FAQs. Yes, they are more than 120 chars long.  They may take you quite a while to get through, but it is very helpful for the exam.
  4. Google for AWS Solution Architect Associate Exam Tips or AWS Developer Associate Exam Tips.  That’s probably how you found this post so you’re ahead of the game.  Read the tips people give.
  5. If you are working full time, and have a family, allow 3-4 months per test.  Yeah, it takes that long, but hey you’re probably smarter than me.
  6. The test is at least a year behind the AWS services. AWS is undergoing such rapid innovation that the certification exams have a hard time keeping up.  Here, and google searches really pay off as they will tend to keep you at the current state of the certification exams, vs the current state of AWS.

Experience with the AWS Solutions Architect Associate exam:

Took this exam in Jan 2017. The largest topics on this exam were VPCs, S3, and EC2, with a bit of Route 53 thrown in for good measure.  Take the course.  You need to read the S3 FAQ (yes the minimum file size is 0 bytes), and understand VPCs, including NAT instances.  Know all your HTTP return codes.  Know SQS vs SNS. Know Alias records, A records, and the rest of Route 53. I recall mutiple security questions – read the well architected framework and AWS security best practices in addition to the Shared Responsibility model document.  All of this is good practical knowledge in addition to being essential to scoring well on the exam.

I took this exam first and felt it was pretty difficult.  I scored in the 80s and was happy to achieve the score.  Some of the questions are straight single answer multiple choice, but many are pick 2 and even some pick 3 answer variations.  These are not fun.

Experience with the AWS Certified Developer Associate exam

Took this exam at reinvent 2017 (November 2017). Having completed the Solutions Architect exam made this exam easier.  As you’d guess, it is more developer centric, but also has a fair amount of overlap with the Solutions Architect. The overlap areas are VPC, S3, Route53 and a bit of EC2 (I think we all know what happens to instance based storage with the instance terminates, heh?). SQS and SNS were also represented by about 5 or so questions on the Developer Associate exam.  I think there was 1 question on SWF.

Where the exams differ is the Developer exam is heavy on DynamoDB – at least 3 questions on calculating different kinds of read and write throughput. Also, there are specific questions on API cals. Read the S3 API, DynamoDB API, and understand how Federated authentication works (AssumeRoleWithWebIdentity, AssumeRoleWithSAML).

There were one or two questions featuring API syntax, but if you are firmly rooted in the principles, you can pick the right answer without memorizing the syntax.  CloudFormation, ElasticBeanstalk and the SDKs were covered at a high-level with a few questions (certainly know what languages are supported for each).

While I won’t give away the specific questions on the exam, there is one that I found so humorous that must be shared. The question had to do with legitimate endpoints for SNS and one of the choices was Named Pipes.  Now that was a blast from the past!  I almost laughed out loud in the exam.  Whomever wrote that question, I salute you.

Know your limits for both Certification Exams

Found it handy for studying to create a table of minimums and maximums for various services in AWS.  This is accurate as of Nov 2017, but beware that these can and do change.  But then again, you have a year before they update the exam.  Hope it is helpful.  Good luck!

S3 object size
Single PUT limit is 5G, but should use multi-part upload for anything larger than 100Mb
S3 buckets
Call AWS to raise limit
S3 Availability
99.9 for IA
99.99 for Standard
1 byte
DynamoDB block size
1K writes
4K reads
Eventual consistent Reads are 2/sec, Strongly consistent Reads are 1/sec, All Writes are 1/sec
DynamoDB BatchWriteItem
25 items, up to 16MB
DynamoDB BatchGetItem
100 items, up to 16MB
DynamoDB Query
1Mb max returned
DynamoDB Global Sec Index
5 max
partition key can be on any attribute
SQS Default Visibility Timeout
30 sec
12 hours
Extend the timeout by calling ChangeMessageVisibility
SQS Message Delay
15 mins
SQS Message Size
Billed in 64K chunks
SQS Requests
1 message
10 messages
Up to 256K
SQS retention
14 days
SQS Long Polling
20 sec
Maximum long polling time out is 20 seconds for SQS
SNS Topics
256 chars
SWF Retention
1 year

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