-
-
As a network administrator, you must be able to setup directory mapping to IP address in accordance with manufacturer recommendations. The Domain Name System (DNS) is one of the most important components of Internet infrastructure. If DNS is unavailable, you’ll have difficulty finding resources on the Internet and, likewise, others will be unable to find you. That’s because DNS is the phone book that translates names such as www.nytimes.com to Internet protocol (IP) addresses such as 199.239.136.245, and vice versa. DNS saves us from having to remember the IP addresses of all of our favorite sites, and it allows Web pages to link to others by name, not by IP address. Finding hosts by name allows IP addresses to change over time, allowing sites to grow, change location, or reconfigure. But, DNS does a whole lot more than just name-to-address mapping. Understanding the basic structure, function, and operations of DNS is an important foundation for all modern-day IT professionals.
DNS is a hierarchical, distributed database with delegated authority. The “delegated authority” part means that you’re responsible for providing a way for Internet users to look up an IP address associated with your organization’s domain. Many organizations let their ISPs manage DNS for them, but that’s a risky proposition at best. A configuration mistake or failure at your ISP can make your company appear offline for at least a portion of the Internet. A political issue could cause you to lose control of your domain information. And, unless you’re your ISP’s largest customer, you have to wait in line with everyone else when you need to make a change to one of your DNS records.
DNS holds the key to your existence on the Internet, which is why you want to control DNS for your domain. DNS is even more than that. DNS is an anti-phishing mechanism, it helps your organization to reject email spam, and it’s a privacy mechanism that helps to hide your internal network topology. Here are just a few ways DNS helps in these areas:
- Anti-phishing. Imagine how quickly your personal information would be lost if you couldn’t trust the identity of your online bookseller or bank. When DNS is working correctly, it helps you to reach the real site, not the imitation one run by an identity thief.
- Anti-spam. Do you think that you get a lot of spam? You’d be getting a lot more if DNS weren’t working for you. Your mail server can verify domain names on incoming email messages, helping to weed out spam. New DNS mechanisms, including the Sender Policy Framework (SPF,openspf.org) or DomainKeys (DKIM, www.dkim.org), identify who is allowed to send mail on behalf of a domain so you can reject email from imposters. Real-time blacklists (RBLs) let your mail server quickly check to see whether a sender is a known spammer or a known infected machine. RBLs such as www.spamhaus.org use DNS as a lightweight query-response mechanism for checking the addresses of email senders.
- DNS reveals to external clients only what you want the public to see about your network. Likewise, it lets internal users and servers see whatever is appropriate for them to see. DNS helps you mask addresses by giving them different names depending on whether they’re accessed from the inside or outside of your network, helping to increase your network’s security.
-
Leave a Reply
You must be logged in to post a comment.