Exam Prep Questions

Question 1	Which well-known network port number does DNS use? A. 21 B. 23 C. 53 D. 25
A1:	Answer C is correct because DNS uses well-known port number 53 for its network communication. Answer A is incorrect because port 21 is used by ftp . Answer B is incorrect because port 23 is used by telnet . Answer D is incorrect because port 25 is used by smtp for email purposes.
Question 2	Which signal would you send to the in.named process to turn off debugging? A. HUP B. USR1 C. INT D. USR2
A2:	Answer D is correct because the USR2 signal is sent to the in.named process to turn off debugging. Answer A is incorrect because the HUP signal causes in.named to reread its configuration files. Answer B is incorrect because the USR1 signal increases the debug level incrementally each time it is sent. Answer C is incorrect because the INT signal causes in.named to dump a snapshot of the DNS database to an ASCII file.
Question 3	Which two files are involved in the configuration of a DNS client? Choose 2. A. /etc/named.conf B. /etc/nsswitch.conf C. /etc/resolv.conf D. /etc/inet/ hosts
A3:	Answers B and C are correct because the two files involved in configuring a DNS client are /etc/nsswitch.conf and /etc/resolv.conf . Answer A is incorrect because the /etc/named.conf file is the master configuration file used to configure a DNS server; it is not used to configure a DNS client. Answer D is incorrect because the /etc/inet/hosts file is used to provide hostname resolution through the use of local files; it is not used by DNS.
Question 4	In a DNS zone data file, what does the resource record type AAAA mean? A. It identifies a name server for the domain B. It identifies a hostname entry with an IPv4 address. C. It identifies a hostname entry with an IPv6 address. D. It identifies an alias for a hostname.
A4:	Answer C is correct because the AAAA resource record type (or quad A) identifies a hostname entry with an IPv6 address. Answer A is incorrect because this describes the NS record type. Answer B is incorrect because this describes the A record type. Answer D is incorrect because this describes the CNAME record type.
Question 5	The DNS daemon process in.named is started only if which file exists? A. /etc/named.conf B. /var/named/named.run C. /var/named/named_dump.db D. /etc/nsswitch.conf
A5:	Answer A is correct because the file /etc/named.conf is the DNS server master configuration file and must exist before the daemon process will start. Answer B is incorrect because the file /var/named/named.run is used to store DNS server debug output. Answer C is incorrect because /var/named/named_dump.db is the file used to store a DNS database snapshot. Answer D is incorrect because /etc/nsswitch is used by the DNS client; it has no effect on whether the DNS server process starts.
Question 6	What is the maximum number of DNS nameservers that can be specified in the /etc/resolv.conf file? A. 1 B. 2 C. 3 D. 4
A6:	Answer C is correct because a maximum of 3 DNS nameservers can be specified in the /etc/resolv.conf file, making answers A, B and D incorrect.
Question 7	Which signal would you send to the in.named process to reread its configuration file? A. HUP B. USR2 C. INT D. USR1
A7:	Answer A is correct because the HUP signal causes in.named to reread its configuration files. Answer B is incorrect because the USR2 signal is sent to the in.named process to turn off debugging. Answer C is incorrect because the INT signal causes in.named to dump a snapshot of the DNS database to an ASCII file. Answer D is incorrect because the USR1 signal increases the debug level incrementally each time it is sent.