IPv4 Communication and Loopback

Question

IPv4 Communication and Loopback

sysengineer (Electrical)

(OP)

3 Sep 15 20:00

Is it possible for a network adapter to have more than one IP address? in other words can an adapter simultaneously communicate using more than one IP address and on more than one subnet?

If not then on a DHCP enabled network is it possible to change the adapter settings manually to some arbitrary IP address on any subnet and start communicating successfully?

Also, out of curiosity I ran a netstat command on my current machine and found there were several TCP connections established using my 192... IP address however there were several connections established on the loopback IP address 127.0.0.1. What typically is the loopback address used for on a Windows machine?

IRstuff (Aerospace) · Answer 1 · 2015-09-03 20:14:37

One obvious use of the loopback address is to snuff the DNS of ads on web pages. DNS only occurs if the local machine doesn't know the IP address of the data that's being fetched, so by a priori assigning the loopback address to ad servers in your Hosts file, the local machine will not be able to retrieve ads from the server farms.

If you really want to get into the details of your posting, you should go to Tek-Tips.com, which is the sister site of this one, but is almost entirely geared for computer hardware and software questions.

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xwb (Computer) · Answer 2 · 2015-09-03 21:32:49

Yes it can have more than one IP address

If you go into the IPV4 adapter properties

1) Switch off "Obtain an IP address automatically" - this is the DHCP option
2) Set an address to use and the subnet mask
3) Click on advanced
4) Add more addresses and different subnet masks

When you've OKed all the dialogs, pop up a cmd prompt and type

ipconfig /all

You should see all the addresses. You normally need to do this if you're receiving broadcast as well as multicast

sysengineer (Electrical) · Answer 3 · 2015-09-03 21:45:51

Thank you so how about on a DHCP enabled network? Is it possible for the DHCP server to lease more than one IP address? Or how about simultaneously having a DHCP leased address and an address set on local machine?

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IPv4 Communication and Loopback