Revision 1 DNS Records in a zone • Zones consist of a number of records • • • • • • • A records – host records in IPv4 AAAA records – host records in IPv6 PTR (pointer) records resolve an IP in to a hostname CName (canonical name) – alias of one name to another MX record – mail exchange record to locate mailservers NS record – identifies nameservers for a domain SOA – start of authority specifies information about the zone Getting record information dig is used to query domain name servers Eg : dig bangor.ac.uk Getting specific record types • Pass the record type to dig • Eg : dig bangor.ac.uk MX Reverse lookup • Use the option –x Linux Nameservers • Use the package bind • Configuration file is /etc/named.conf • Listens on port 53 (UDP) • Zones are referenced in named.conf Creating a new zone • Add the zone to named.conf Reverse resolution zones Similar to forward resolution statement Blocks of the IP address are reversed .in-addr.arpa is included after them zone “1.0.10.in-addr.arpa” IN { type master; file “domain.com.rr.zone”; allow-update {none;}; }; • PTR records in zone file <last IP digit> • 20 IN IN PTR PTR <FQDN of system> dev.mydomain.com.