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Understanding DNS records – A, CNAME, ALIAS, URL, MX, CERT, NAPTR, PTR, TXT

A record

Maps a name to IP addresses.

CNAME record

Maps a name to another name. It should only be used when there are no other records on that name.

ALIAS record

Maps a name to another name, but can coexist with other records on that name.

URL record

Redirects the name to the target name using the HTTP 301 status code.

  • The A, CNAME, and ALIAS records cause a name to resolve to an IP. Conversely, the URL record redirects the name to a destination. The URL record is a simple and effective way to apply a redirect for one name to another name, for example redirecting www.example.com to example.com.
  • The A name must resolve to an IP. The CNAME and ALIAS records must point to a name.
  • Never use a CNAME record for your root domain name (e.g. example.com).

MX Record

Mail Exchanger (MX), similar to A name records but entirely devoted to sending and receiving e-mail.

CERT

CERT records store site certificates as part of the DNS information.

NAPTR Records

A rare record type that’s used to map telephone numbers and e-mail addresses for VoIP and SIP servers.

PTR Record

PTR directs IP traffic to domains.

TXT Record

TXT is used commonly to verifying domain ownership. It holds data sender policy framework (SPF) .

 

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Migrate Large WordPress sites with Duplicator plugin.

We will do the task with wordpress duplicator plugin.

Step One: Current Hosting

  1. Make Zip archive of all files and folders.
  2. Download it to your PC or you may copy the zip file to the targeted hosting location using Cron Jobs [Follow this].
  3. Install Duplicator plugin (https://wordpress.org/plugins/duplicator/)
  4. Create New Database Only Package with Duplicator.
    • Goto Duplicator ❯ Packages ❯ click “Create New” button
    • On Step 1 Setup ❯ Archive ❯ check “Archive Only the Database”
    • Build package then download installer and archive files

Step Two: Targeted new hosting

  1. Upload the downloaded zip file or or you may copy the zip file from current hosting to the targeted hosting location using Cron Jobs [Follow this].
  2. Extract the zip file to targeted location. After extraction, remember to remove or delete the zip file from targeted location.
  3. Upload the duplicator archive zip and installer.php. DO NOT extract the zip.
  4. Create a new database and connect user to it. Save database name, database user name and password.
  5. Point your website to new hosting by changing nameservers. It may take 15minutes to 72hours to propagate the change.
  6. After propagation, you can browse installer.php. Ignore override warning.
  7. Click next and put host (localhost), database name, user, password. Test database.
  8. Click next and install database.
  9. Now login to your wordpress admin with current username and password.
  10. That’s all.

 

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Check Opened and Closed Ports on Linux

  • List opened ports with protocol name : 
    netstat --listen --tcp
  • List opened ports with protocol number : 
    netstat --listen --tcp -n
  • Check a Port 587 is Not Blocked. For example, Port 25 
    telnet yourdomain.tld 25
    • 220 response confirm port not blocked
    • Unable to connect or Connection refused confirm port blocked.

 

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Dovecot Mail Service In Linux – Start, Stop, Restart, Reload, Status, Enable

Dovecot is an open source IMAP and POP3 email server for Linux/UNIX-like systems.

  • Start: 
    service dovecot start

    or

    systemctl start dovecot
  • Stop: 
    service dovecot stop

    or

    systemctl stop dovecot
  • Restart: 
    service dovecot restart

    or

    systemctl restart dovecot
  • Reload: 
    service dovecot reload

    or

    systemctl reload dovecot
  • Status: 
    service dovecot status

    or

    systemctl status dovecot
  • Enable Dovecot Mail Service on Boot 
    chkconfig dovecot on

    or

    systemctl enable dovecot
  • Dovecot default configuration file location 
    vi /etc/dovecot/dovecot.conf