Multiple SOA records?

[Chris Buxton]

Pull a zone transfer using dig, of any zone that you have zone  
transfer access to. The output will start and end with an SOA record.  
For example:

$ dig @localhost localhost axfr
; <<>> DiG 9.4.1-P1 <<>> @localhost localhost axfr
; (3 servers found)
;; global options:  printcmd
localhost.		86400	IN	SOA	localhost. root.localhost. 42 10800 900  
604800 86400
localhost.		86400	IN	NS	localhost.
localhost.		86400	IN	A	127.0.0.1
localhost.		86400	IN	SOA	localhost. root.localhost. 42 10800 900  
604800 86400
;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed May  7 07:15:35 2008
;; XFR size: 4 records (messages 1, bytes 134)

Chris Buxton
Professional Services
Men & Mice

On May 7, 2008, at 3:30 AM, Lars Hecking wrote:

> Kevin Darcy writes:
> [...]
>> traininghott.com definitely seems to have a standards-conformance  
>> issue
>> in the way it handles SOA queries
> [...]
>
> Hhm, I think I would disagree here. After all, their name servers do  
> return
> SOA records when queried directly, even if they are too many.
>
> The interesting bit is, if I let my own name server do the querying,  
> I get
> SERVFAIL:
>
> ; <<>> DiG 9.3.3rc2 <<>> @server traininghott.com. soa
> ; (1 server found)
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 49324
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
>
> ;; QUESTION SECTION:
> ;traininghott.com.              IN      SOA
>
> ;; Query time: 331 msec
>
> but a tcpdump/wireshark analysis shows that there were two answers  
> (the
> SOA RRs, two name servers, and nothing in the additional section;  
> 2/2/0
> in tcpdump output). This means that the querying server, which runs  
> BIND
> 9.4.1_P1 btw., has decided to discard the response. I guess this kinda
> clarifies my original question "What kind of consequences can I expect
> trying to resolve records in a domain that has more than one SOA?".
>
> Kevin, can you explain
>
>> Note, however, that *transactionally* a zone transfer response  
>> includes
>> 2 SOA RRs.
>
> I cannot find anything on this?
>
>
>