How to choose ios to upgrade

[MrBeginner]

Dear All,
I would like to ask about for IOS version.I saw alot off version in cisco site (Fuji,Amsterdam,Gibraltar). But i don't know which one is the stable.Which one the less vulnerability ? I always choose Suggested Release (with start mark ). 

For Example. When i upgrade my isr 11000 series router.
I saw suggested Release is Fuji-16.9.4(MD). But when i check the vulnerability by using your ios software checker,it found some vulnerability and recommend to upgrade to 16.10.1. But i check 16.10.1 ,i still got some vulnerability too and recommend upgrade to anther version.
So let me know how to choose your IOS version without vulnerability ? what is the recommend ? let me know MD version is already fix their issue ?

[Leo Laohoo]

So the new IOS-XE version is expressed in three "groups": X.Y.Z.
Look at the "Z" or last number.
IF the number is higher than 4, like 16.6.6 or 16.9.4, then there is a likelihood that the version is stable.
Next, look at the release date. You want to look at a version that has been recently been released (for the last 6 months).

Finally, Release Notes.  Read it very, very carefully.  

[MrBeginner]

Hi Leo,

Can you explain me more detail with example,please ? I would like to request.

I didn't understand yet because of my less knowledge.

[Leo Laohoo · Accepted solution]

If I look at the IOS-XE available for the 1100-series routers I am presented with:

• 17.1.1
• 16.12.2s
• 16.11.1 (deferred because it is a train wreck)
• 16.10.3
• 16.9.4
• 16.8.3
• 16.7.3
• 16.6.7

I look at the last numbers and pick the ones with "4" and higher.  That leaves 16.9.4 and 16.6.7. 

16.6.7 was released on 01 October 2019 and 16.9.4 was released on 25 August 2019. 

I know that 16.6.X will have one more release soon (and nothing else).  So that is out. 

16.9.X will have a release in the next 4 weeks.  16.9.X will have another (or so) year of support. 

This means 16.9.X is a good candidate.  Now go and read the Release Notes.