[bind10-dev] DNS server use cases and BIND 9 compatibility

[fujiwara at jprs.co.jp]

Hi, 

I think that we need to consider DNS server use cases and BIND 9
compatibility on BIND 10.

BIND 9 supports all use cases in one program "named".

Will BIND 10 support all use cases in one configuration ?

I classified DNS server use cases and made some consideration.

Do we need to discuss such topic in next meeting ?

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DNS server use cases:

There are several user categories: Small scale users, DNS Hosting,
TLDs, ISPs.

1. Small scale users

   * Characteristics
     - Number of zones is small.             ( < 1,000 ? )
     - Each zone size is small.              ( < 1,000,000 ? owner names )
     - Number of slave DNS servers is small. ( < 10 ?)
     - Zones are not changed frequently. (A few times par day ?)
     - They operates some resolvers.
   * Includes
     - Most organizations (enterprises, universities, ...)
     - Indivisuals
   * Use cases
     - Most of them operates three types of DNS servers.
       (a): Master server
            - loads zone information from local files
	    - acts as an authoritative DNS server
	    - transfers zone information to their Slave DNS servers using *XFR.
       (b): Slave servers
	    - receive zone information from their Master DNS server using *XFR.
	    - act as an authoritative DNS server
       (c): Resolvers
       	    - act as full-resolvers.
       (c1): Resolvers with static zone
	    - it has the organizations' zone information which
	      may be received by *XFR or loaded from zone files.
       (c2): VIEW function sometimes used
             to separate authoritative function and resolver function.
       (c3)  Some users operate authoritative function and resolver function
             in one IP address.

2. DNS Hosting

   * Characteristics
     - Number of zones is large.             ( > 10,000 ? )
     - Each zone size is unknown (small ?)
     - Number of slave DNS servers is large. ( > 10 ?)
     - Zones may change frequently.
   * Use cases
     - (d): Special authoritative DNS server
            
           They may not use AXFR/IXFR/NOTIFY to transfer their zone 
             information to their slave DNS servers.
           They may use RDB backend. (DLZ in BIND 9?)
           Or, They may use file copy (over SSH/RSYNC/file system)
       	     and reload their slave servers.

3. TLD

   * Characteristics
     - Number of zones is small.             ( < 10 or 1000? )
     - Each zone size is large.              ( > 1,000,000 owner name)
     - Number of slave DNS servers is large. ( > 20 ?)
     - Zones may change frequently.          ( each 1 or 5 or 15 minutes )

   * Use cases
     - Most TLDs use three types of DNS servers.
       - (e) ZONE master (Manages TLD zones, transfers TLD data
                          to Transfer servers. using AXFR/IXFR/NOTIFY out)
       - (f) Transfer servers (Trasnfer TLD data to Authoritative DNS servers.
                               using AXFR/IXFR/NOTIFY in/out)
       - (g) Authoritative DNS servers (offer DNS service,
                                        transfer using AXFR/IXFR/NOTIFY in)
         == (b)?

4. ISPs

   * Operate many resolvers.

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  BIND 9 offers all function in one binary "named".
  It offers all use cases: (a)(b)(c)(e)(f)(g)

  BIND 10 auth with RDB backend may support (d).
  BIND 10 auth with in-memory db may support (a)(b)(f)(g).
  BIND 10 full-resolver may support (c).

  NSD supports (a)(b)(f)(g) without IXFR-out function.
  Unbound supports (c) without (c2)(c3).
    Unbound can offer static zone written in configuration file.
    Unbound cannot retrieve zone information via *XFR. (BIND 9 can do).

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--
Kazunori Fujiwara, JPRS <fujiwara at jprs.co.jp>