I am curious about the purpose of the ACLs created on the WLC 9800.

[JJJHL]

Those ACLs are
ACL on 9800.

not user generated
It appears to have been created by WLC itself.

Could you by any chance know the purpose of each ACL?

-IP-Adm-V4-Int-ACL-global

-implicit_deny

-implicit_permit

-preauth_v4

-meraki-fqdn-dns

[Scott Fella]

I think what would be better is to review of IOS acl's in general.  These are just default, you can use as a template or even add to them if you want.  They are not applied unless you apply them.  Just look and research understanding/configuration IOS acl's to just get a basic idea of how to create one and apply one.  Then its easier to look at what you have, not just on the 9800 and understand what the all is doing.

[Rich R · Accepted solution]

There are some ACLs which are autoconfigured when you use webauth and their contents are based on the webauth config you provide - and those can't be changed manually, or if you do IOS will overwrite your changes. For example:
IP-Adm-V4-Int-ACL-global
IP-Adm-V4-LOGOUT-ACL
WA-sec-<redirect portal IP>
WA-v4-int-<redirect portal IP>
Most of the names are self-explanatory.

meraki-fqdn-dns doesn't seem to have any content (ACEs) by default so I'd guess that it will only be populated if you do something that requires it, like migrating CW APs to the Meraki dashboard.

[JJJHL]

thanks.

Do you know what implicit_deny/permit is for?

[Rich R]

Presume you mean what are they used for - no idea - could be anything - but the names are paradoxical because they are both explicit rather than implicit LOL
9800#sh ip access-lists implicit_deny
Extended IP access list implicit_deny
10 deny ip any any
9800#sh ip access-lists implicit_permit
Extended IP access list implicit_permit
10 permit ip any any

More accurate names would have been permit_all and deny_all but who are we to question the wisdom of the devs...