What spell or ability lets me detect a creature’s resistances/vulnerabilities? [duplicate]

I wonder if there is a spell that, when cast, gives me information about a certain creature, like its vulnerabilities and resistances. For instance, when fighting a Bronze Dragonborn, this spell would divine for me that they have Lightning Resistance.

Besides spells, is there a non-magical way to do so? Survival-check, Arcana, History, Insight? I have a hard time placing this under any one of those skills, if at all…

I’d be most interesetd in divination spells along the lines of Detect Magic / Detect Good and Evil, but if there is any other (magical) effect that would yield these results I’d like to know too.

Since the caster of the Zone of Truth of spell knows whether a creature failed the save, can they use it to detect hidden/invisible creatures?

I’m DMing for a 5e party that includes a cleric, as many parties do. This cleric has found (what appears to be) an interpretation of the wording of the “Zone of Truth” spell that makes it even more powerful than it seems to be intended to be.

His idea is that since Zone of Truth tells you when a creature succeeds or fails the save, he could use it to detect if a hidden or invisible person enters the radius, as it would tell him that someone succeeded or failed the save.

Is this true? if not, is there any official example that specifically says it’s not true?

(And, if Zone of Truth WOULD do this, is there any way to prevent such a detection, as I know the party will do this a ton, and if it’s something they can do, I don’t want to deny it outright, but some villains may have countermeasures)

Nessus detect more open ports than nmap

I scan my site via namp , I only see 3 ports open.

nmap -sV {ip}                                                               Starting Nmap 7.80 ( https://nmap.org ) at 2020-01-25 09:42 EST                                     Nmap scan report for {ip}                                                                Host is up (0.023s latency).                                                                        Not shown: 997 filtered ports                                                                       PORT    STATE  SERVICE VERSION                                                                      22/tcp  open   ssh     OpenSSH 6.6.1p1 Ubuntu 2ubuntu2.13 (Ubuntu Linux; protocol 2.0)              80/tcp  open   http    nginx                                                                        443/tcp closed https                                                                                Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel                                              Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .      Nmap done: 1 IP address (1 host up) scanned in 11.72 seconds   

When I scan that same IP on Nessus, I see

Output

Port 2052/tcp was found to be open Port    Hosts 2052 / tcp / www     www.my-site.com Port 2053/tcp was found to be open Port    Hosts 2053 / tcp / www     www.my-site.com Port 2082/tcp was found to be open Port    Hosts 2082 / tcp / www     www.my-site.com Port 2083/tcp was found to be open Port    Hosts 2083 / tcp / www     www.my-site.com Port 2086/tcp was found to be open Port    Hosts 2086 / tcp / www     www.my-site.com Port 2087/tcp was found to be open Port    Hosts 2087 / tcp / www     www.my-site.com Port 2095/tcp was found to be open Port    Hosts 2095 / tcp / www     www.my-site.com Port 2096/tcp was found to be open Port    Hosts 2096 / tcp / www     www.my-site.com Port 443/tcp was found to be open Port    Hosts 443 / tcp / www  www.my-site.com Port 80/tcp was found to be open Port    Hosts 80 / tcp / www   www.my-site.com Port 8080/tcp was found to be open Port    Hosts 8080 / tcp / www     www.my-site.com Port 8443/tcp was found to be open Port    Hosts 8443 / tcp / www     www.my-site.com Port 8880/tcp was found to be open Port    Hosts 8880 / tcp / www     www.my-site.com 

Why they’re different? Are they hidden ports?

What nmap commands should I use to same amount of port listed from Nessus ?

How did Vice detect voting machines connected to the internet? [closed]

https://www.vice.com/en_us/article/mb4ezy/top-voting-machine-vendor-admits-it-installed-remote-access-software-on-systems-sold-to-states

What method would you use to determine if a machine is a voting machine? do they give off a unique signature? Did someone give them a list of all IP addresses associated with voting machines and they pinged them to see if they were online?

the article is very scarse on details, yet it referneces a group of security experts

Does casting the Detect Evil and Good spell on a killed monster reveal anything?

If I kill some kind of evil creature like a zombie, chuck it into a shallow grave and burn its remains, would casting detect evil and good on the skeletal remains reveal anything?

Or do destroyed/slain monsters immediately stop registering for such effects?

The spell does not specify if the creature needs to be alive, dead, or whole. However, it may cease to be considered a creature if it is dead; I do not know.

The detect evil and good spell description reads:

For the duration, you know if there is an aberration, celestial, elemental, fey, fiend, or undead within 30 feet of you, as well as where the creature is located. Similarly, you know if there is a place or object within 30 feet of you that has been magically consecrated or desecrated.

Additionally, would you know that it was undead? Or just that it is one of those types of monster?

Also, does it remain ‘undead’? Once undead, always undead?

I assume this spell only reveals if the monster is one of the types in the list (not which one?), and not alignment like I think perhaps past editions of D&D have done.

Does Telepathy give the ability to detect thoughts?

The Monster Manual 1 states in the Pseudodragon entry (Pg. 210):

Telepathy (Su): Pseudodragons can communicate telepathically with creatures that speak Common or Sylvan, provided they are within 60 feet.

It later in the the passage states (Pg. 211):

PSEUDODRAGON COMPANIONS
A pseudodragon may very rarely seek humanoid companionship. It stalks a candidate silently for days, reading his or her thoughts and judging his or her deeds.

No where in the entry does it say the pseudodragon has the ability to listen to thoughts. So does telepathy automatically give the ability to do this?