you are administrator for the local DNS server for your company, and you have be
ID: 3809524 • Letter: Y
Question
you are administrator for the local DNS server for your company, and you have been tasked with manually adding the IPv6 reverse-mapping zones for your company's domain to the server's config file. The IPv4 domain name for your company's Web site is abcxyz.com, and the IPv6 domain name is abcxyz-v6.com Your must know the Ipv4 and the Ipv6 addresses for your company's domain and any subdomains,such as marketing.abcxyz.com and marketing,abcxyz-v6.com or sales.abcxyz.com and sales.abcxyz-v6.com, so you can configure the corresponding A and AAAA records as well as the ip6.arpa reverse-mapping zone names for each IPv6 address. Determine where you find this data, and then, once you have gathered that information, construct the begining of an IPv6 reverse-mapping zone based on that information. Use the $ORIGIN control statement and the following format:
$ORIGIN
PTR record
PTR record
Explanation / Answer
An AAAA query for a particular domain will return all the records with AAAA in the answer section where it will not trigger any additional section processing. As given, ip6.arpa is a domain used for reverse-mapping of the IPv6 address namespace, with the domain rooted as ip6.arpa. Each level of subdomain under the ip6.arpa represents 4 bits out of the 128 bit IPv6 address, with the low order to high order bits moving from left to right.
IPv6 addresses in the ip6.arpa domain is represented as nibbles, separated by colons and with ip6.arpa suffix. Each nibble is a hexadecimal character. In reverse mapping, each character in IPv6 address is made up of nibble. Nibble is 4 bits, a half byte.
All A record query types must be redefined in order to perform both A and AAAA additional processing.
Below is the A and AAAA record for a domain name
domain-name IN A 72.246.164.170
domain-name.v6 IN AAAA 2001::2d57:c4f8:8808:80d7
IPv6 reverse-mapping zones on a DNS server contain numerous PTR records and must contain one SOA record and one or more NS records. In case of IPv4 reverse mapping which is infrequently delegated to the server administrator, IPv6 supports delegated reverse mapping. In turn administrator can create the reverse-mapping zone files using the ip6.arpa domain name.
$ORIGIN f:e:0:0:b:a:9:8:7:6:5:0:4:3:0:0:2:1:0:0:1:2:3:4:8:b:d:0:1:0:0:2.ip6.arpa
1.a PTR sample.domain-v6.com
1.b PTR mail.domain-v6.com
For IPv6, any address which is forward mapped using AAAA RR will be reversed mapped as RR PTR, because PTR records must point back to a valid AAAA record.
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