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Migration Made Simple - Switching Your Internet Connection and Keeping Emailing Flowing

Presented June 12, 2007 at NYExUG Meeting. Migration Made Simple - Switching Your Internet Connection and Keeping Emailing Flowing. Ben Serebin Network Consultant REEF Solutions ben a t reefsolutions . c o m. Overview. How Often Do You Change ISPs that Impact the Email Server

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Migration Made Simple - Switching Your Internet Connection and Keeping Emailing Flowing

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  1. Presented June 12, 2007 at NYExUG Meeting Migration Made Simple - Switching Your Internet Connection and Keeping Emailing Flowing Ben SerebinNetwork ConsultantREEF Solutionsben a t reefsolutions . c o m

  2. Overview • How Often Do You Change ISPs that Impact the Email Server • Preparing for the ISP Change • DNS-Day Change • Mission Accomplished? • Understanding the Importance & What reverse DNS (rDNS) Is!

  3. Changing ISPs is a Big Deal For Email Servers • When selecting a new ISP for hosting email, here are a few recommedations: • you want a static IP address (technically possible with dynamic, but a lot more complex). • the ISP does not block SMTP traffic to external hosts (meaning, you don’t need to relay via the ISPs mail relay (e.g. smtp.yourisp.com) • ISP supports reverse DNS (rDNS), this is NOT DNS related in the normal sense, but managed by the ISP. Reverse lookups are named as per your instructions by calling your internet connection vendor and request that an IP be named “owa.reefsolutions.com”. Normally, the standard rDNS entries for your connection would be 98-23-32-45.biz. us.nyc.vzn.com) • Service Level Agreement guaranteeing outage repair times and bandwidth minimums

  4. Preparing for the ISP Change (no migration yet) • Check the new internet connection using a laptop. Make sure internet is working and bandwidth is accurate. • Document on paper old IP settings (IP, Subnet, Gateway, & DNS) and new IP settings (same as above). • The 2 DNS records you need to add & change are host and mail exchanger records. Host are also known as A or alias records. And Mail Exchangers are also known is MX records. Commonly referred to as A and MX records. • Question: if your ISP is High Speed Net and you use their email (stuckwith@highspeed.net) and you move to another state without High Speed Net. What happens to your email? Now, folks using ISPs DNS are frequently in for similar problems? So, if I need to preach about hosting your DNS externally, see my January NYExUG presentation (2007.01 NYExUG Presenting of Externally vs. Internally Hosted DNS Recommendations and Best Practices)

  5. Hunt for the DNS Owner… • Find out who hosts your domain’s DNS. You can determine this by checking your NS records for your domain name. One website is dnsstuff.com. Example below is the NS record for reefsolutions.com. So, now we know, operationdns.com is the vendor hosting DNS for reefsolutions. See Type NS, and then answer.

  6. Average MX Record (standard company MX) • samsserif.com has 1 MX entries (see type column). • So, all email goes to mail.samsserif.com. This would be your current IP connection with the existing ISP. Preferences (aka cost, priority) tell order for other mail servers to connect to samsserif.com So, preference of 0 means, primary server. Associated A record not shown below. • Every MX record also has an A record which would be mail.samsserif.com 23.23.65.110 (example). Remember, every MX has an associated A record.

  7. Implemented 2 MX Records (for switchover) • samsserif.com has 2 MX entries (see type column). • Create a new A record for the 2nd ISP’s IP address. Set the Time To Live (see next slide for TTL explanation) to 600. 600 is in seconds, so that is 10 minutes. Keep in mind if OWA entry is different (e.g. create just an A record for OWA). • Preferences (aka cost, priority) tell order for other mail servers to connect to samsserif.com So, preference of 0 means, primary server. Lower the #, higher the priority. So below, 2 MX records, 1st (mail.samsserif.com) for old IP from current ISP, and the 2nd (mail2.samsserif.com) for new IP from new ISP.

  8. TTL of a DNS Record Means How Old Are You? • TTL = Time to Live. This entry is used to tell other DNS servers how long to keep this entry in their cache. This entry (TTL) is present in all DNS entries. So, in this example b.reefsolutions.com, mail.pghost.com, and spamcop.reefsolutions.com have a TTL of 7200. This is in seconds, so converted that is 2 hrs of caching. This will vary by DNS hosting provider. So, this tells other DNS server to check every 7200 seconds for any changes. • So, if I change the MX record, how long does it take to go live?

  9. DNS-Day Planning • Use DNSstuff.com to confirm MX records are valid and resolving. • Make sure your local Windows DNS Server is not using the old ISP’s forwarders entries. Windows 2000/2003 DNS does not need ANY ISP DNS entries, since it’ll find out the answers itself using the root DNS servers. Speed up and improve the accuracy of your network’s DNS by using the natively built-in DNS root hints. • Switch IP on firewall to implement new ISP’s connection. • Test outbound message to a web based email solution (e.g. Yahoo, Gmail, etc). • Test inbound message from inbound web based email solution.

  10. Completing Migration – Reverse DNS Importance! • Once email is flowing in. Change IP address for old MX record (mail.samsserif.com) to new IP. Increase TTL to 14400 or similar. Low TTL puts stress on DNS servers and if you do not plan to change IP, no need to waste the bandwidth. Wait 2-3 days, and then remove mail2.samsserif.com DNS entry (A & MX). • Insure the ISP completed the reverse DNS setup for your IP. Protect against being classified as spam and getting rejected. Test using “tracert 69.31.40.115” which shows spamcop.reefsolutions.com. Enter your company IP instead to test. Means, the IP has an entry at the ISP level showing the requested entry versus ISP assigned “66-174-20.myhomevzw.com [66.174.20.4]”. Remember, this is a ISP related IP entry change, and not DNS related. It might be confusing since it is called reverse DNS.

  11. Resources for Presentation & Further Information • To check your DNS records and check your DNS timing, use dnsstuff.com. This will convince you to upgrade to Anycast (clustered) DNS. • For Anycast DNS providers see DNSmadeeasy.com [recommend], UltraDNS.com, Netriplex.com, and Akamai.com • Contact your ISP to add a rDNS (aka pointer or PTR record) for your mail server. This is based on an IP address. • If you use hosted virus, spam, etc services for your Exchange Server, make sure you relay your mail via that vendor, otherwise if you do not list an MX record this can cause mail sending difficulties for your server.

  12. Presented January 9, 2007 at NYExUG Meeting Exchange Maintenance Recommendations Ben SerebinNetwork ConsultantREEF Solutionsben a t reefsolutions dot c o m

  13. Basic Maintenance for Your Server Recommendations • Check Event Logs for Exchange Errors. • Test Exchange to receive email via telnet. (http://support.microsoft.com/kb/153119) • Check your Exchsvr\MDBDATA directory to insure logs only are current date. • Launch ESM and make sure Mail Store and Public Store are running. • How Much Free Space is there (SP1 16GB, SP2 75GB)? • ESM under your server name and check the Queues. Make sure they are empty. See next page.

  14. Basic Maintenance for Your Server Recommendations • ESM under your server name and check the Queues. Make sure they are empty. See below.

  15. Presented January 9, 2007 at NYExUG Meeting Thank you for attending the NYExUG User Group Meeting.Benefits of Attending Meetings- pizza- raffle (1GB USB thumb drive)

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