claws's questions

I'm on a LAN provided by an ISP. My computer has its IP address, Subnet Mask, Default Gateway, DNS Servers(using DHCP).

I just wanted to see the MAC addresses of all the computers on my LAN.

1. After applying subnet mask /18 or 255.255.192.0 on my IP I got: 182.3.64.0
2. Which gives me 16384 IP addresses ranging from 182.3.64.0 to 182.3.127.255
3. First and last IP addresses cannot be used as they are Network address and Broadcast address respectively.
4. So, My subnet or local network contains 16382 hosts/computers. Right? In other words these 16382 hosts are behind single router.

I want to see the mac addresses of these hosts. SO, I pinged all of them and the picture shows the result:

My thinking:

I didn't understand why they all have same Mac Address. But now if I think little bit more about it. 16382 hosts behind a single router means too much of broadcast traffic (ARP broadcast). Which is not desirable. At the same time they cannot be connected to different routers because that would mean they are on different networks. May be they are on different VLAN (I don't know much about VLAN but I just know that it helps reducing the broadcast traffic).

I don't understand what is my problem. Kindly identify what am I getting wrong?

EDIT: The MAC address I'm receiving is the MAC of my default gateway.

I'm a moderate web developer. I haven't managed any high traffic websites. Generally, I observe that only high traffic websites are down for maintenance. stackoverflow.com will also go down for maintenance.

I always wonder. What kind of maintenance do they do? I mean, the process is automated.

user request --> web server --> server side programs --- > Database server.

What is there to maintain?

I bought a domain name on example.com & I want to use free webhosting on 110mb.com

By default name.com integrates services of Google apps. Name server entries are

ns1.example.com 
ns2.example.com 
ns3.example.com 
ns4.example.com 

When I registered on 110mb.com it gave me two addresses

ns1.110mb.com 
ns2.110mb.com

This is where I'm lost. The concept is that "Domain name should point to an address of the server where the website is hosted" right? Then

1. Why are these 4 entires by default. How exactly is it working?
2. Should I remove these 4 and then add 110mb.com servers or just append 110mb.com server addresses to name.com ones.

I would like to use google apps. If I change these name server addresses would that remove google apps? I especially want to use email service of google. And I really don't understand what is CNAME, MX, or something something. I want to learn about these stuff & how it exactly works.

When I search for webhost tutorial. I'm unable to find any fruitful results.