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The importance of Backups and DNS

On Sat 11th May 2013, 13:34 Jonathansays:

DNS and backups are both very important things both at home and on a company network and both are things I've had to work on this week - for myself and other people.

DNS, the Domain Name System, is what translates an address that we humans use (e.g. www.jonsdocs.org.uk) into the IP address numbers computers use (e.g. If you can't resolve an address to an IP address you may find you can't go anywhere. If I poison your DNS I can send you to the wrong place, possibly to install bad software or to harvest your login credentials. Sometimes DNS poisoning is simply used to make money - the most recent high profile example being DNSChanger which infected millions of computers.

If you have a business network, or a network with Microsoft's Active Directory, DNS is critical to the running of your infrastructure. I recently received a report a customer was unable to access the Internet, they'd put a workaround in place by using a public DNS server but then found their Outlook clients wouldn't talk to their Exchange server. Outlook couldn't find the server because the public DNS server didn't know about the server's local address.

Their problem stemmed from an incorrect network card setup on the server although it had worked fine for years so I'm not sure what caused it to change. Anyway, the problem is solved - DNS is really important.

So, backups. It's no secret I've been burned by lacking or incomplete backups before. I killed a harddisk (as in I really killed it - laptops don't like fists) and went to my backup only to find I'd excluded some critical files. I won't be doing that again...

The last 2 weeks I've had to work on some laptops that appeared to have failed. Neither laptop had a backup of the files so the process of data recovery began. Fortunately, the harddisks were still alive in both cases and the data was fine (and promptly burnt on to several backup DVDs).

Windows users of Vista and above (or Windows Server 2008 above) can use Windows (Server) Backup which comes built in to Windows. Capable of making an image backup enabling you to restore your computer from harddisk failure the built in software is really quite helpful. Windows XP Pro users had NTBackup which was also useful. If you don't have a backup product built into the Operating System there's always the free alternatives out there or a hand written script.

Importantly, if you do take backups make sure they're not kept with your computer or laptop. Put them offsite somewhere (perhaps do a harddrive swap with a friend in another part of town) so if your computer is stolen (or worse your house burns down) you don't lose the backup too.

My backup completed about 30 minutes ago...