Multiple A or CNAME?

[Bill Moseley]

At 04:55 PM 06/03/00 -0600, Lee Howard wrote:
>>I'm mixed up about when to use CNAMEs when I have two names pointing to the
>>same IP number.

>From The Linux Network Administrator's Guide by Olaf Kirch:
[snipped]

>Because many systems will also use /etc/hosts for DNS resolution, I
>interpret the above to mean that you use an A record when there is an entry
>in /etc/hosts for it.  If there is no entry for the system in /etc/hosts,
>then use CNAME.  Okay, okay, I know this isn't black-and-white this way,
>but this is how *I* interpret it.
>
>There are admins out there who only ever use A records and never use CNAME,
>which works just fine.  Outside of the NS, MX, and SOA pointing
>requirements, It's your preference, I'd guess.

Alright.  So it's OK to use multiple A records to the same IP.  And then, I
guess, on reverse, I can just pick which name I want to return in
in-addr.arpa requests.

I'm trying to make sure I get my setup correct before making it publicly
available.  Most of it makes sense, but seeing how I'm just now learning
I'm sure I have mistakes.  So, maybe it's just simpler to list my zone file
and see if anyone can point out errors. 

I'm thinking about using Granitecanyon as my secondary -- or just run my
own.  If I only run my own DNS will fail it my link is down, but if my link
is down I can't be reached anyway.

I'm only running one Internet-accessable machine at this point, but will
probably bring another online soon to split up the services.

I do have a few questions below.  Any tips would be greatly appreciated!

@                       1D IN SOA       mardy    root (
                                        2000060305      ; serial
                                        1D              ; refresh
                                        1H              ; retry
                                        1W              ; expiry
                                        1D )            ; minimum


                        ;; Name servers for hank.org

                        1D IN NS        ns1
                      ; 1D IN NS        ns2   ; not online yet
                        1D IN NS        ns1.granitecanyon.com.
                        1D IN NS        ns2.granitecanyon.com.


                        ;; Mail servers
                        ; Can this point to, say, mail.hank.org. and 
                        ; have an A record for mail?

                        1D IN MX        5  mardy


                        ;; IP number mapping

                        1D IN A         63.205.225.170


                        1D IN RP        info.hank.org. info.hank.org.
info                    1D IN TXT       "Bill Moseley  -- Hank.org"
                     

                        ;; Specific machines

gateway                 1D IN A         63.205.225.169
mardy                   1D IN A         63.205.225.170
ns1                     1D IN A         63.205.225.170
dialup1                 1D IN A         63.205.225.171
;ns2                    1D IN A         63.205.225.174

                        ; internal machines, use /etc/hosts instead
;selly                  1D IN A         192.168.0.99
;cory                   1D IN A         192.168.0.98

localhost               1D IN A         127.0.0.1


                        ;; Aliases - for client computers to use
                        ; I'm not sure why these shouldn't or should be
                        ; A names instead.
smtp                    1D IN CNAME     mardy
pop3                    1D IN CNAME     mardy
ftp                     1D IN CNAME     mardy
www                     1D IN CNAME     mardy




Bill Moseley
mailto:moseley at hank.org