How to manually input DNS information on a Mac

Often when you connect to a network, your computer will be provided with certain network information automatically, such as IP address, gateway, and DNS settings.  However, there are some times when you will need to type in the DNS information manually.  This post shows you how to enter DNS information for your network on a Mac.  (The wording may vary slightly depending on which version of Mac OS X your computer is running.)

- Click on the Apple icon in the upper left corner of the screen.
- Select System Preferences.
- Select Network.
- Select the network whose DNS settings you want to change (if it's not already selected).
- Select Advanced.
- Select DNS.
- Click on the plus sign (+).
- Type in (or copy and paste) the DNS server's IP address.
- Press the <ENTER> or <RETURN> key.
- If you have a secondary DNS server, input that information as well by repeating the previous three steps.
- Select OK.
- Select Apply.

What is DNS and what does it do?

DNS (Domain Name System) is a service that translates domain names into IP addresses.  With DNS, you're able to type "www.yahoo.com" into a web browser and have the browser actually load the Yahoo! web page.  If you didn't have a DNS server to rely on, that action would be impossible.

We use domain names (such as "yahoo.com" or "google.com") to label websites because the words make sense to us and we can remember them.  But to a computer, domain names are completely arbitrary and meaningless.  Computers use IP addresses to identify other computers.  So the computer that hosts Google.com has an IP address, and it's this IP address that your computer looks up when you go to Google.com.

DNS is what enables your computer to translate the words "google.com" that you type into your web browser into Google's IP address.  Your computer doesn't know where on the Internet Google.com is, or what it represents, if it can't attach an IP address to it.  All computers (and other devices) on the Internet have an IP address, and these IP addresses are how they identify themselves.

When you log on to a network, or when you connect to the Internet through an Internet service provider, your computer is probably assigned an IP address.  But at the same time that it receives its IP address, it also receives the location of that network's DNS server or servers.  This information is vital to performing many functions, including sending email, loading web pages, and downloading content.

Without a DNS server, your computer wouldn't be able to load any websites that you type into your browser (unless they were looked up earlier and remain in the DNS cache).  You could be connected to your network, and everything is good, but if your computer doesn't know where the network's DNS server can be found (or if that DNS server is down) then you can't do anything based on domain names.  Without a DNS server, you would have to know the IP address of any website you wanted to visit.

As stated earlier, most networks and Internet service providers automatically provide client computers with the location of at least one DNS server.  If your ISP doesn't have a DNS server, or if that server isn't working, there are free DNS servers online that you can point your computer to.  Your computer would use these DNS servers in the same manner, looking up any domain names that you feed it and attempting to resolve them into IP addresses.

A DNS server is a lot like a bilingual human translator.  If you are having a conversation with someone who only speaks Spanish, the translator knows what you say, and what the other person says, and it can communicate this information between the two of you.  If you say, for example, "Can I please have a napkin?" to someone who only speaks Spanish, that sentence is meaningless to them without someone to translate it.  The napkin in question could be sitting two inches from that person's hand, but until someone can translate your request into the other language, you can't get your napkin.  DNS works in much the same way.

(Originally published on Helium.com, March 2012)

How to troubleshoot scan to email problems from a scanner or multifunction printer

Many scanners and all-in-one printers (or multifunction printers) offer the ability to scan documents or images to an email address.  Depending on the device and your email server, this process can range from seamless to stressful.  If you're having problems setting up scanning to email, or if it worked before and it's not working now, here are some places to start the troubleshooting process:

- Check Your Settings

Sometimes settings can get entered incorrectly.  Other times, a power outage, power spike, or other event can cause the scanner to "lose" certain information, and you may need to enter it again.  Make sure the email server settings are entered correctly, including user name and password (if applicable), email server name, port number, and any protocols being used (SMTP, SSL, etc.)  If the password for that email account has recently been changed, it will need to be updated in the scanner's settings.  If your email server doesn't require a user name and password, make sure the authentication setting on your scanner is turned off.

If you're not sure what your email server settings are, this article lists the common settings for some popular email servers.

- DNS

If your scanner is connecting to your email server by its host name (such as smtp.gmail.com) rather than its IP address, you will need a valid DNS server in order to translate the name to an IP address.  Check to be sure your DNS server IP address is stored in your scanner, and also make sure that server is up and running.  If you don't have a DNS server, you can use Google's DNS server (8.8.8.8) or Comcast's DNS server (75.75.75.75).

- Gateway

In order to be able to communicate with devices outside your local network, the scanner will need to know your gateway IP address.  Typically, this will be the IP address of your router.  If you don't know your gateway address, this article can help you find it.

- Network Connection

Check the network connection from your scanner.  If the scanner is a multifunction device, you can check the connection by printing something to it.  Otherwise, you can try pinging it from a computer or other device on your network.  If the ping isn't successful, there may be a problem with the network cable, the scanner's network interface card (NIC), or an intermediary device on the network such as a hub or switch.

- Email Server

The problem may lie with your email server, rather than your scanner.  Try to send an email from your computer, using the same email account the scanner is set up to use.  If you don't have access to send emails from that account, ping the email server from your computer.

- Internet Access

Make sure you can get online from your local network.  If you can't, reboot your router or contact your Internet service provider.

- Gmail Authentication Issues

Gmail sometimes requires users to verify who they are when they log into their Gmail account.  It's a good security feature, but it can prevent automated devices (such as a scanner) from logging in.  Log into your Gmail account from a computer and see if you are required to verify your identity.  If so, you may need to turn the verification feature off in order to be able to send emails from your scanner.  Sometimes, if Gmail won't let you authenticate from the scanner, try logging into your Gmail account from a local computer and then log right back out, and that will correct the issue.

- Spam Folder

If your email provider doesn't recognize the "from" email address used by the scanner, it may send the scanned file to your spam or junk folder.  This is especially likely to happen if the message doesn't have a subject line, or if there's no email body, just the attached file.  Adding the scanner's email address to your contacts list can usually prevent this issue.

(Image courtesy of Pixabay)