What is an  'A' records

Posted on 2009-02-16
Last Modified: 2012-05-06
Hello, i have taken over a role as part of the firewall team.  In place we have 4 firewalls, 1 set of 2 is for failover(Checkpoint for outside and ASA for inside) and 2 firewall routers.

We have mobile phones that sync up for emails for our users that talk to the exchange server.
We have a certifcate for these phones on the ISA server.

The certificate for these phones was pointing at one firewall router but i had to ring the DNS company and get them to change it to point at the other side for testing.

i asked them (i was prompted by someone else) Could the following A record be ammended please?

My question is just - what is this A record all about?  What is the relevance of it and why do i have to know which firewall router to point it at.  Is it because it affects the routing of the mobile phone sync?

any advice is welcome, Kevin
Question by:ohareka
    LVL 19

    Expert Comment

    When a device needs to connect to a resource it looks up the destinations IP address using it's Fully Qualified Domain Name.  In this case the phone looks up the IP address for  It does this using a DNS lookup.  By ammending the A record with a new IP you have effectively changed the address that is returned to the phone.  
    LVL 51

    Expert Comment

    by:Keith Alabaster
    The A record is simply the name given to the dns entry that associates an ip address with the Fully Qualified Domain Name. for external dns this is normally controlled by your ISP un less you look after it yourself of course.
    LVL 2

    Accepted Solution

    'A' record is 'Address' Record in DNS.   what ever domain name you are using to find a computer on the network/internet is routed to the IP 'Address'.

    Author Closing Comment

    thanks to all 3 answers.  Much appreciated, K
    LVL 51

    Expert Comment

    by:Keith Alabaster
    lol - shame you only accepted one then but no worries :)

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