I'm very confused by Cisco versions, but perhaps I'm just over thinking it. Are IOs versions and ASA versions the same? E.g. If I have an ASA 5510 and I type

show version

and it comes back with

Cisco Adaptive Security Appliance Software Version 8.3(2)
Device Manager Version 6.9(4)

does that mean it's running IOS 8.3?

Or will accept IOS 8.3 level commands?

Or do ASA devices have their own version separate from the IOS versions?

(p.s. the version numbers above are made up so they won't make sense).

More generally, how do you know which commands a Cisco device is going to accept? If you show up at a clients and start trying to do named access lists (which apparently started with IOS 11.2?) how do you know if they are going to work? Or do you just try, curse and revert to older commands on the fly if they aren't recognized?

I've searched long and hard and nothing seems to show what versions which commands should work on.

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Commented Aug 13, 2017 at 6:06

1 Answer 1


Cisco has a whole bunch of different operating systems for a variety of products:

  • IOS runs on most Cisco routers and switches.
  • IOS XE is a more modern, modular version of IOS.
  • IOS XR runs on high-end routers.
  • NX-OS runs on the Nexus line of datacenter switches.
  • ASA OS runs on Cisco ASA devices.
  • AireOS runs on Access Points.
  • And I'm probably forgetting a lot of other devices and appliances.

Version numbers for all these operating systems are unrelated. And even within the same OS there can be different release trains for different platforms.

If you want to know which commands should work on a specific device, you can check the Cisco Feature Navigator.

  • Good answer. I'd also add there are a lot of similarities, but nothing guaranteeing identical operation / features / command structures.
    – Eddie
    Commented Feb 10, 2016 at 7:48
  • There's also PIX OS that runs on the older PIX firewall boxes, but these have largely been replaced by the ASA series. You can however still encounter loads of these in older installations.
    – Stuggi
    Commented Feb 10, 2016 at 11:33
  • Excellent information. However, the Feature Navigator doesn't seem to list ASA OS information, nor does it allow one to find the name of a feature from the command... Is there a generally known level required for common features? E.g. Standard ACL's only until version X, then Extended, then Named in version Y. Commented Feb 11, 2016 at 22:35
  • 1
    This page lists features per release for Cisco ASA OS, but it's not an easy page to find things on. You might take a look.
    – RobinG
    Commented Feb 12, 2016 at 6:22

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