DNS Basics and Mail Security

IT:Network:Apps

Domain Name System Terms Hosts Root Servers Zones Name Resolution Reverse and forward Lookups CName MX Records NSLookup IPconfig

DNS DNS is a database with its own set of tools

used to provide maintenance and querying capabilities

Root Servers are DNS servers that maintain info about all other Domains

Topmost root domain is unnamed and is simply the “.”. Next is the Top-level, ie.◦ .com, .edu, .gov, .int, .net, .org, .mil, etc, etc

Record Types ‘A’ Record

◦ Specifies a host address Myserver.mycompany.com IN A 127.0.0.1

CNAME◦ Canonical name define aliases for their true host name. Mapping multiple names to a single IP.

MX ◦ Mail exchange record provides information for message routing for a specified domain.

NS◦ Lists other NAME SERVERS

PTR◦ POINTER RECORD is a reverse of a host (A) resource record because it provides information for

reverse lookups SOA

◦ Start of authority SRV

◦ Services locator _MSDCS _SITES _TCP UDP

NSLOOKUP◦ SET TYPE=ANY <ENTER>◦ DOMAIN.COM

Testing DNS

Register domain name◦ www.networksolutions.com◦ www.godaddy.com

Create records

Configuring DNS Records for Email

http://www.spam.com/ Not!

Spam is the use of electronic messaging systems (including most broadcast media, digital delivery systems) to send unsolicited bulk messages indiscriminately.**www.wikipedia.com

Spam

Office 365◦ Filtering built in

Spam

Custom Office 365 Policies

Spam

Google (postini)

Spam

Custom Configurations

Spam

Support offered in Exchange 2010 as well as legacy Exchange◦ 2003Intelligent(?) Message Filtering

Exchange 2010 Content Install anti-spam agents on the Transport Hub

◦ http://technet.microsoft.com/en-us/library/bb201691.aspx

◦ .\Install-Antispamagents.ps1 Automatic update for Antispam signatures

◦ Enable-Antispamupdats –IPReputationupdatesenabled $True –Spamsignatureupdatesenabled $True –Updatemode Automatic –Microsoftupdate requestscheduled

Spam

Security Appliances◦ http://www.spamhelp.org/appliances/

3rd Party(off-site) SPAM filtering solutions◦ Postini

http://www.google.com/postini/index.html

◦ Others http://www.spamhelp.org/services/listings/managed-

anti-spam/

SPAM