Do you know how to Nmap ?

Unanswered Question
Sep 21st, 2008

Hi there,

My question is not about Cisco. So, Im so sorry but I need your help now.

Maybe, do you know how to nmap ?

I try to find out some hostname(computer name) with nmap. But I can't do that because it's not appear on the nmap.

Anyone knows this ?

If anyone let me know, I'll appreciate so much.

Thanks again.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
cleidh_mor Sun, 09/21/2008 - 23:42


nmap should automatically do a reverse dns lookup on an ip when you scan it, although there are easier ways to do it than using nmap.

If you're trying to scan a host using nmap and it gives you a message about the host not being up, try with -P0 (that's -P[zero]). nmap will try to ping a host to determine whether it's up or not before scanning so hosts blocking ping will exhibit this behaviour.

For other options, see the man page, or


shsong21 Mon, 09/22/2008 - 15:54

Hi there,

Thanks for your answer.

By the way, I have one more question for you.

We have one AD(Active directory) server on our network. When Im running nmap into AD area, I can see hostname but in outside of AD area I can't see hostname.

You know the hostname means netbios.

I don't know why.

I can't find out the answer at that site.

Do you know that ?

Thanks again.

cleidh_mor Mon, 09/22/2008 - 23:20


NetBIOS uses broadcast traffic so it won't get past any routers you have on the network. The most likely answer is that when you scan from another area, your local DNS server can't resolve the IP.


shsong21 Tue, 09/23/2008 - 04:58

Hi there,

Thanks for your post.

I know that Netbios using broadcast traffic.

As I told, I can see the hostname into AD(Active Directory) domain area.

But others area is not.

So, how do I can see it into AD area ?

Do you know that ?

Thanks again.

cleidh_mor Tue, 09/23/2008 - 05:08

Probably because if you're in the AD domain, the local dns server will resolve the names for you.

shsong21 Tue, 09/23/2008 - 16:09

Hi thre,

Thanks for your answer.

As you told , we have local DNS server into local network.

As I told you, I can see the hostname with Nmap into AD domain area but can't see it on other vlans( I mean outside AD domain area on local network).

For example,

AD domain area network : 172.16.11.x

normal vlans network : 172.16.1.x ~ 172.16.9.x

Our local dns server is into normal vlans network.

But I can see the hostname into only AD domain area.

I don't know why.


cleidh_mor Tue, 09/23/2008 - 23:46

Is the local DNS part of the domain? I would normally expect your DC to be running DNS as well. Are there any acls in the way?


This Discussion