What’s the difference between a Mac Address and an IP Address?

MAC and IP addresses are both key components to network, but they serve different purposes, and are visible in very different ways.

//

What is the difference between a Mac Address and an IP Address? Are both traceable back to your computer? And can you hide them? If by hiding them is your computer safer from hackers. Also, are the free versions as good as the ones you buy?

Well, the last one is easy to answer: there’s no concept of free versus paid IP or MAC addresses. As you’ll see in a moment, IP addresses are assigned as part of connecting to a network, and MAC addresses are assigned at the time hardware is manufactured.

Even hiding a MAC or IP address is a concept that doesn’t quite apply, but we’ll get in to that too.

And whether MAC or IP addresses are hidden or not, if you connect to a network these are not the kind of things you should be spending your time worrying about to stay safe from hackers.

A MAC (or Machine Access Control) address is best thought of as a unique serial number assigned to every network interface on every device. And by unique, I do mean unique; no two network cards anywhere should have the same MAC address.

You can see your network interfaces MAC addresses using the command prompt in Windows XP using ipconfig /all:

Ethernet adapter Local Area Connection 2:
        .
        .
        Physical Address. . . . . . . . . : 00-1D-60-2F-4B-39
So your MAC address doesn’t make it out very far. And knowing it certainly doesn’t help anyone do anything, good or
bad.

Each network adapter on your computer will have one.

MAC addresses are typically used only to direct packets in the device-to-device portion of a network transaction. That means that your computer’s MAC address will be in network packets only until the next device in the chain. If you have a router, then your machine’s MAC address will go no further than that. Your router’s MAC address will show up in packets sent further upstream, until that too is replaced by the MAC address of the next device – likely either your modem or your ISP’s router.

So your MAC address doesn’t make it out very far. Even if someone knows your MAC address, that knowledge certainly doesn’t help anyone do anything either good or bad.

An IP address is assigned to every device on a network so that device can be located on the network. The internet is just a network after all, and every device connected to it has an IP address so that it can be located. The server that houses Ask Leo!, for example, is at 72.3.133.152. That number is used by the network routing equipment so that when you ask for a page from the site, that request is routed to the right server.

The computers or equipment you have connected to the internet are also assigned IP addresses. If you’re directly connected, your computer will have an IP address that can be reached from anywhere on the internet. If you’re behind a router, that router will have that internet-visible IP address, but it will then set up a private network that your computer is connected to, assigning IP addresses out of a private range that is not directly visible on the internet. All internet traffic must go through the router, and will appear on the internet to have come from that router.

Metaphors are always a tad difficult, but let’s try this:

An IP Address is kind of like your postal address. Anyone who knows your postal address can send you a letter. That letter may travel a simple or complex route to get to you, but you don’t care as long as it makes it.

The same is true of packets of data traveling on a network like the internet. The IP address indicates where a packet is destined, and the system takes care of getting it there. A letter may or may not also have a return address so you know who to write back to – a TCP/IP address always has a return IP address.

A router can perhaps be thought of as a company’s mail room. You may send a letter to “Complaint Department, Some Big Company, Some Big Company’s Address”. The postal service will get that letter to the company. The company then notes that the letter needs to go to the complaint department, and routes it there using inter-office mail. And of course, all your outgoing mail is picked up by the inter-office mail courier and routed to the external postal service as needed.

When you’re behind a router the same thing sort of happens – all of the packets destined for you are actually addressed to your router. It’s the router that then determines which of your computers that packet might be meant for, and routes the packet appropriately.

In both cases – corporate mail room or networking router – the actual physical location of your office or the actual local IP address of your computer is not visible to the outside world.

A MAC Address is kind of like the color, size and shape of your physical mail box. It’s enough that the postal carrier (your network router) can identify it, but it’s unique to you, there’s no reason that anyone other than your postal carrier might care what it is, and you can change it by getting a new mailbox (network card) at any time and slapping your name (IP address) on it without affecting your delivery.

As I said, it’s not a perfect metaphor, but perhaps it’ll help get some of the basic concepts across.

Finally, a word about staying safe from hackers.

MAC addresses aren’t part of the discussion, simply because they never travel beyond your local network, and they can’t be hidden as they’re simply required for networking to work. Many network adapters allow you to override the MAC address, but even so it still identifies your computer on the local network.

IP addresses are also required for networking to work. The network has to know what computer to send data to. You can, in many cases, use things like anonymization services and the like to appear to be coming from a different IP address, but that doesn’t change the fact that your machine is still reachable by some IP address.

Merely being connected to the internet, by whatever address you happen to use, requires that you take steps to stay safe. There’s ultimately no way to completely “hide” your IP address without disconnecting from the network. What you should be doing are the classical steps to internet safety: get behind a router, keep your system up to date, run anti-malware scans, backup regularly and so on.

Since I know it’ll come up, and as I’ve discussed over and over and over and over again, an IP address does not allow someone to find out your physical location or identity without law enforcement intervention. Similarly, you cannot find out someone else’s physical location or identity without involving the authorities.

There are 45 comments:

  1. Ken B Reply

    It’s funny you use a postal metaphor here. My father once asked me how his computer “knows” how to talk to a computer across the country. I used a postal metaphor to describe how Internet traffic is routed.

    When you mail a letter, how does the letter “know” how to get across the country? It doesn’t have to. The postman who picks up the mail only has to know how to get it from your mailbox to the local post office. Someone at the local post office only has to know that a letter going to Florida gets sent to the White Plains post office. From there, someone only has to know that it goes to the New York City branch. From there, someone sends it on a truck to Miami. From there, it’s put on a truck to the local post office. And from there, it’s put on a truck to be delivered.

    At each step, all that’s needed to be known is which direction to send it on its next step along the way.

  2. JohnE Reply

    Leo – one part of the original question asks about the difference between IP addresses you get ‘for free’ and those you buy. I think this is asking about the difference between a dynamic and a static IP address – most ISPs will give you a dynamic IP address as standard but will charge you for a fixed IP address; a dynamic IP address is fine if you just use email and the internet, but if, for example, you want to run your own web server, and host it yourself on your own computer, you need a static IP address.

  3. Chandra Sekaran K Reply

    It gives a good picture about the IP and MAC addresses.
    Does the MAC address also go along with the IP address as hidden-part of the Header Details of the Email to the receiving PC / Server ?

    No. The mac address only travels as far as the next piece of networking equipment in the path. So it probably only goes as far as your router.

    -Leo

  4. Chandra Sekaran K Reply

    IP and MAC – Very nicely differentiated.
    I have some doubts. Will the MAC address also go with the IP address as part of the Header details along with the Mail exchange ? Can the Mail be tracked back to the MAC no (ie., the Mail originating PC )?
    What is the real purpose MAC Address ?

  5. rahman Reply

    Dear Sir Leo:

    Hope you will fine and healthy. I’m so happy from your site and your information to take us and u solve our problems.
    Sir i have Three quetions.
    1. what is diffrent between Table and Query in Access programm?

    2. What is different between routing protocols and routed protocols?

    3. What is different between ISA server and Proxy server?

  6. Chuck Reply

    Very interesting in fact I understood your metaphor. Perhaps you can answer a question.
    I’m installing a new machine, I’m connected to the internet but cannot open my browser (page cannot be displayed). Checking my IP address it appears as all letters.

    Any help will be greatly appreciated

    Uh, no. An IP address should never appear as all letters. (OK, an IPv4 address should never appear as all letters, the newer IPv6 is another matter, but not something you should be seeing anyway.) I’d have to know exactly how you’re looking at your IP address to know what it is you’re actually seeing.

    -Leo

  7. Dave Reply

    Would love to know the answer to this above post as well.

    IP and MAC – Very nicely differentiated.
    I have some doubts. Will the MAC address also go with the IP address as part of the Header details along with the Mail exchange ? Can the Mail be tracked back to the MAC no (ie., the Mail originating PC )?
    What is the real purpose MAC Address ?

    A MAC address uniquely identifies every network interface. It travels no further than the next router or equivalent network interface. It does not appear in email headers as it makes no real sense to be there.
    -Leo
  8. Jason Reply

    Why would someone want the same mac address as me? I just found out through my Internet provider that some one else had the same mac address as me, which is why my internet wasn’t working. How does that happen, and should I be concerned?

  9. Octavius Reply

    Dear Sir,

    This is indeed a useful site.

    Please advise me the followings:
    Is it mandantory to get a MAC address (OUI/IAB),
    even if, I used the ethernet device on a LAN only?

    Thank you.

    Regards,
    Octavius

  10. Jetrue Hudson Reply

    Dear Leo
    Can you connect Macs and PC’s to the same server?
    How?
    Thanks,Jetrue

  11. DINESH Reply

    why cant we replace IP system by MAC system, bcoz MAC address is going to be unique as similar to IP Address instead of sending source IP address we can transmit Source MAC address, why cann’t we do that? i am also not clear “MAC Adress travels no further than the next router or equivalent network interface” !!!!

  12. Jason Scully Reply

    For how long the MAC Address remains stored in the router’s memory?

    Depends on the router, and how busy it is.

    - Leo
    23-Jul-2009

  13. shubham Reply

    Dear sir,
    The ip address at any given time in the internet is unique to a host. if so then why is mac address even required?
    can’t ip address be used to recognise the host inside the network too?

  14. Abhishek Reply

    Dear Leo,
    this information is really very valuable.
    I have a keen interest in network security methods in current times and I wanted to ask something to clarify some things for myself …

    I have a system that connects to a router which further connects to my modem.
    when i do ipconfig/all, i get the mac address of my ethernet port, not the router or modem, which i can check using the interface for the respective device. if my understanding is correct, my mac address does not go past the router, coz it changes there to the address of the router which further changes to the address of the modem and so on …
    however, at the site “http://www.ipaddresslocation.org/find-mac-address.php” it uses java to find the mac address of my ethernet card.

    this is what brings me to my question… as you said, “So your MAC address doesn’t make it out very far. Even if someone knows your MAC address, that knowledge certainly doesn’t help anyone do anything either good or bad.” just as the site used java to find my original mac address, can’t a similar process be applied to trace a person/machine’s location on the internet.
    also, there are proxy service providers, both free and paid softwares, that change the external ip address of a machine. in theory, is ip address tracking the only professional way of tracing a person/machine’s original address?
    my understanding is that the sender’s ip is included in the chat/email/post that is received at the other end, and these proxy servers/softwares change that header info to keep it anonymous. i know legal intervention is required, but is the packet info that contains the IP address the only way of tracing the origin or does it also have mac address info of the originating machine/person?
    Please help me understand this better.
    Thanks in advance.
    Best Regards.

  15. Steve Reply

    Please be clear…we are trying to trace an e mail…we have an IP…probably a public access point…now we want to try to find the mAC address of the computer that sent that mail from that public connection??? Is it possible? Does the router retain that address? This access point was used to access a hushmail account and that account send the mail we are interested in tracing.

    The router sees too many MAC addresses to remember them all. I suppose some routers could be keeping a log, but in general they do not.

    Leo
    09-Oct-2009

  16. Melissa Boyd Reply

    Hello Leo,

    A question on the last question. Is it possible for anyone to find the MAC address from an email sent?

    Best,
    M

    Nope. And it’d be useless if it did.

    Leo
    17-Apr-2010

  17. awais Reply

    Hello Leo,

    i wan to know..that

    Why we use Ip addresses whereas we have MAC addresses? What is the reason behind that

  18. Reif Masters Reply

    I think your answers may be misleading, depending on the root of the question & cause for privacy. Consider the following circumstances:

    1) One wants to send an anonymous message to an email address. One wants the recipient to read the message, but one does NOT want the recipient of the message to know the ACTUAL identity of the email sender.

    2) One opens up a

  19. manish kumar Reply

    hi….can i know the MAC address (through the sent mail’s header information) of the system from where i am sending a mail using my gmail account.
    please help me……

    No. The MAC address is not included in mail headers.

    Leo
    27-Dec-2010

  20. Abi Reply

    Hi..Leo
    i wanna know that how the webcam chat rooms sites banned us?what those sites use to identityfy us?
    I usually use vagaters.com for webcam chat with friend all over country . Some day ago i did the text flooding so vagaters.com blocked me and say pls return after 3 hrs.
    i came back to the vagaters.com and tried to login but it return me access denied! Now i m not able to login vagaters.com.i m trying to login each time but i cant always i found Acess Denied!
    So what can i do should i need to change my IP address or MAC address?

    No way for me to know. It depends on the technique’s that particular site uses.

    Leo
    19-May-2011

  21. Abi Reply

    Hi..Leo
    i wanna know that how the webcam chat rooms sites banned us?what those sites use to identityfy us?
    I usually use vagaters.com for webcam chat with friend all over country . Some day ago i did the text flooding so vagaters.com blocked me and say pls return after 3 hrs.
    i came back to the vagaters.com and tried to login but it return me access denied! Now i m not able to login vagaters.com.i m trying to login each time but i cant always i found Acess Denied!
    So what can i do should i need to change my IP address or MAC address?
    Note-vagaters.com do not require any login info and email address for login.Every one can login as guest using any of user name and u can also login using another username,no passward require.

  22. guest user Reply

    why is there a pair of these addresses? why does this network system need two different addresses for any entity? couldn’t it be possible for a global network system to depend on just one unique address, e.g. IP or MAC or sth else, provided that whatever it is, it will be unique.

    The MAC address is part of the underlying Ethernet protocol, and identifies your computer only to the hardware connected directly on that same network segment. It does NOT travel across routers. The IP address is part of the TCP/IP protocol which is implemented on top of Ethernet, and identifies your computer on a larger network such as your local LAN and/or the internet.

    Leo
    23-Jul-2011

  23. snert Reply

    Thank you again, Mr Leo!
    That cleared up a lot of what I was wondering about MAC.

  24. Cindy Gioffredi Reply

    I like your metaphor/analogy. I’ve tried to explain that concept not so much from a “How to be safe from hackers” perspective, but to answer the question “Why didn’t I get my e-mail?” or “Why did it take so long to send/receive my e-mail?” I like your explanation better than mine. They’re similar, but your description makes more sense! I usually start by trying to clarify that an address is an address – Internet or home address – & that it’s a unique, identifiable thing. Something that can be found on a map or schematic. Half the time I lose them after using the word schematic, but either way – lose them there or not – I can NEVER find the words to make it understandable! I’ll continue my explanation by saying, “It’s like having mail carrier pick up a letter from a sender’s address with the end result being that it will be delivered to the receiver’s address. The recipient will usually receive the it in the time frame expected but – depending on all the magic (good & bad) behind the scenes – it might arrive late or never at all. Then I try to define magic thustly: If the mail truck crashes for some unexplainable reason & every piece of mail becomes ash, you’ll never get your delivery & probably never know why; if the mail person gets sick there might be a delay while the post office finds a subsitute carrier; maybe there’s roadwork on your street & the mail person has to take a detour that results in a longer drive or walk so it takes longer than it should . . . Then I’ll add that sometimes a package is so big & heavy it has to be broken down into individual pieces & delivered separately – but there’s a magician type of thing that reassembles the smaller packets into the bigger package before you actually receive it . . . Of course by then they’re saying, “Uh nevermind” or “I’m not asking about SNAIL mail.” Oh boy. Sometimes when someone asks why they didn’t recieve an e-mail I tell them they’d have better luck getting an explanation if they direct their question to the Goddess of Null. I THINK they know I’m trying to be funny! I’m always being asked if I’m a computer tech because I’m crazy or if being a computer tech MADE me crazy. I tell them I don’t know for sure because I’m crazy! Never a dull moment that’s for sure! I hope it’s OK if I use YOUR explanation of data transfer in the future. Thanks Leo! :-)

  25. Nagaraju Reply

    thanks for your explanation , it’s really helped me a lot.

  26. Balwinder Singh Reply

    Hi Leo,
    First time visited your site and found this article very interesting. Thanks a millions for the wonderful information. Just a quick question.. Is there a way to mask or hide my machine information (like OS, browser version, other settings etc) from Java Code or ActiveX or JavaScript being run from a website? Like if a website is trying to get my Device Finger Print, how can I prevent or block or mask that?
    Thanks a lot !!
    Singh

  27. crashN2u Reply

    I think a better way to convey the mac address is to liken it to a post office box. You have a specific box number assigned to you. It’s how the postal worker knows how to route your mail to you. And if you decide to change it later, you can.

  28. Thomas Reply

    In response to the Vagaters comment: Vagaters uses a mix of data available through the browser and http connection to try to identify banned users. Regular IP or cookie bans, which most other chats use, have proven to be inefficient.

    Since the site had been abused for illegal activity in the past and is not monitored 24/7 bans do not last 3 hours, but 7 days.

    The site uses the camamba.com chat technology, where a ban indeed lasts 3 hours, hence the misleading message.

  29. Jim Levin Reply

    Leo -
    Thanks for the insightful piece. As you have noted in many other posts, the recipient of an email sent from Google, Yahoo, etc can often glean the IP address from which it was sent. How about the *sender’s* MAC address? Is this logged in an email’s header? Also, can the known IP address be used to view a log of MAC addresses that accessed the router?
    Thanks,
    J Levin

    I’ve never seen or heard of a MAC address in an email header. As for the router log: it depends on the router, whether it even logs such a thing (I know of none that do), and how securely it’s set up.

    Leo
    21-Jan-2012
  30. Hariharan S Reply

    Hi Leo,
    Very well explained and similied. Was very helpful to me in understanding the IP and MAC address. Thank you. Thanks a lot.

  31. Tushar kumar Reply

    Very simply and effectively u clarified my doubts
    Thanx Leo….ur metaphor thing has helped me loat n getting things properly….keep working 4 us

  32. wasim Reply

    very well explained , u really gave me a big smile . I was very much confused initially but now very much relaxed. Post office example was awesome .

    Thanks

  33. Name Reply

    Thank you very much Leo, your explanations have been very helpful – demystifying.

  34. alif Reply

    as ip address has two parts n/w addr part and host address part, n/w address identify network and host address identify the host in that n/w , then proper routing is also possible , then after all what is need of mac address? plz answer i cant be keep confusion for more time. thank you

  35. Nombre Reply

    Well stated Leo. Could you further expand on the difference with a mobile device MAC address vs a standard desktop or laptop? Thanks!

  36. Joao Victor Reply

    Leo,

    Why do I need a MAC address if the package has the destination IP? Can’t it get to the destination only with the IP?

    Thank you,
    Joao Victor

  37. @B! Reply

    hello sir…….
    thank u for ur valuable information…,,
    i may say… actually a worthful class for me.
    so attractiv styl of xplanation.

  38. Mac Reply

    I logged into my wireless network and someone hacked into my network. Can that be traced to the exact location if I provide the Mac Address?

  39. Mark J Reply

    @Mac
    You could only determine who hacked into your account if you know who happens to own the machine with that MAC address. There is no registry where MAC address are stored.

  40. gan Reply

    i have shared my ip adress and mac id with someone can that person harm me any way???

  41. @pal Reply

    I have a doubt . why don’t we deal only with ip addresses . In data link layer we use mac address. Why can not we use ip address instead of mac address in data link layer.

Leave a reply:

Before commenting please:

  • Read the article. Seriously. You'd be shocked at how many people make comments that prove they didn't.
  • Comment only on the article. If you have a new, unrelated question start with the search box at the top of the page.
  • Don't post personal information. Email addresses, phone numbers and such will be removed.

VERY IMPORTANT: because of a rise an comment spam that's making it through our filters any comments that do not add to the discussion - typically off topic or content-free comments - run a very high risk of being flagged as spam and removed.

If you have a new question unrelated to the article above, ask it on the Ask Leo! ask-a-question page.