You may elect to use whatever you wish including IN-addr. The last part of the IPv4 Address (17) is the host address and hosts, from our previous reading, are typically defined inside a zone file so we will ignore it and only use the Class C address base. Note: RFC 2317 uses the CNAME RR to implement the solution as shown in the following zone file fragments. Prior to RFC 2181 '/' was not a legal character for a domain name or label so an alternate construct using '-' could be used instead, for example: $TTL 2d ; 172800 $ORIGIN 64/.192. Each byte (or octet) is comprised of 8 bits; a nibble is part of a byte and consists of 4 bits. (it might not appear so hilarious for non-native users of English - just trust us, it's, at least in this author's opinion, hilarious.) In the context of reverse mapping, each hexadecimal character in the IPv6 address string constitutes a nibble. IPv6 reverse zone names (and skeleton reverse zone files) may be generated using the IPv6 address tool.The result of our manipulations are: IP address =192.1 Class C base = 192.168.23 ; omits the host address = 17 Reversed Class C base = 23.168.192 Added to IN-ADDR. For reverse delegations of $TTL 2d ; 172800 seconds $ORIGIN 23.168.192. To illustrate how this works, we must write each character - with no zero elimination - of the assigned addresses range: Use the IPv6 Calculator to expand IPv6 addresses and automatically generate the reverse zone name. ; Start of Authority RR defining the key characteristics of the zone (domain) @ IN SOA ns1. ( 2010121500 ; sn = serial number 12h ; refresh = refresh 15m ; retry = refresh retry 3w ; expiry = expiry 2h ; nx = nxdomain ttl ) ; name server RRs for the domain IN NS ns1. The individual PTR address labels can become brutally long. Experiment using the IPv6 Address Calculator and reverse map file generator.In order to perform Reverse Mapping using normal recursive and Iterative (non-recursive) queries the DNS designers defined the special (reserved) Domain Name of IN-ADDR. These LIRs are typically responsible for allocating blocks of addresses to customers.Historically IPv4 address were allcated in /8 blocks to RIRs but due to IPv4 address depletion this is no longer possible.In this case the most important part (the highest node in the address hierarchy) is on the LEFT (192) not the RIGHT. ( 2003080800 ; serial number 3h ; refresh 15m ; update retry 3w ; expiry 3h ; nx = nxdomain ttl ) IN NS ns1. If you want to change the host names in the assigned subnet they must be notified to the authority for that Class C address. ;qualified 66 IN CNAME 66.64/27 ;unqualified name 67 IN CNAME 67.64/27 .... Unlike IPv4, where reverse mapping is frequently not delegated to the end user, IPv6 allows and encourages delegated reverse mapping.This is a tad awkward and would make it impossible to construct a sensible tree structure that could be searched in a single lifetime. Generally, this is unacceptable since such requests may encounter indifference, cost or questions. ; definition of our target 192.1/27 subnet ; name servers for subnet reverse map 64/27 IN NS ns1. ; IPs addresses in the subnet - all need to be defined ; except 64 and 95 since they are the subnets ; network and broadcast addresses not hosts/nodes 65 IN CNAME 65.64/.192. 93 IN CNAME 93.64/27 94 IN CNAME 94.64/27 ; end of 192.1/27 subnet ..... ( 2003080800 ; serial number 3h ; refresh 15m ; update retry 3w ; expiry 3h ; nx = nxdomain ttl ) IN NS ns1. ; IPs addresses in the subnet - all need to be defined ; except 64 and 95 since they are the subnets ; network and broadcast addresses not hosts/nodes 65 IN PTR fred. The end user can therefore be responsible for creation of reverse-mapping zone files using the IP6. ARPA domain used for reverse mapping of IPv4 addresses and is shown in Figure 3.2 below. ARPA Reverse Mapping Assume the user has been allocated from a RIR (Regional Internet Registry) or an LIR(ISP/SP) a fairly typical IPv6 range: Note IPv6 block allocations, like many other issues in IPv6, are still relatively fluid but are typically /48 or /56 - exceptionally /64.
A normal DNS query would be of the form 'what is the IP of host=www in domain=mydomain.com'.IPv6 addresses are typically allocated to the RIRs in /12 to /23 blocks depending on demand and cicumstances.The allocation of IP address is essentially a delegation of the authority to reverse map these addresses. Classless Reverse Map Delegation is defined by RFC 2317 which has Best Current Practice status and should be regarded as a definitive reference.Welcome to Linux Questions.org, a friendly and active Linux Community. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration.
Note that registered members see fewer ads, and Content Link is completely disabled once you log in. Visit the following links: Site Howto | Site FAQ | Sitemap | Register Now If you have any problems with the registration process or your account login, please contact us. This guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter.
They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own.