Answer Key Explanations | Solaris 9 Network Administrator Exam Cram 2 (Exam CX-310-044)


Question 1	Answers B and C are correct because a RARP request supplies only an ethernet address. The lookup in `/etc/ethers` provides the hostname, which is then used in the lookup of `/etc/inet/ hosts` to ultimately return the IP address. Answer A is incorrect because `/etc/inet/ netmasks` is used to associate network masks with network numbers . Answer D is incorrect because `/etc/bootparams` is used to provide boot information for diskless clients .

Question 2	Answers B, C, and D are correct. HTTP, DHCP, and Telnet are all Application layer protocols. Answer A (TCP) is a Transport layer protocol, Answer E (ICMP) is an Internet layer protocol, and Answer F (PPP) is a Network Interface layer protocol.

Question 3	Answer B is correct. Sun's implementation of the 1000BASE-LX standard supports distances up to 3000 meters, using fiber optic cable. Answer A is incorrect because 1000BASE-CX uses copper cable up to a distance of 25 meters and is primarily used within wiring cabinets . Answer C is incorrect because even though it uses fiber optic cable, the maximum distance is 550 meters. Answer D is incorrect because 1000BASE-T uses UTP Cat 5 cabling and supports distances of up to 100 meters .

Question 4	Answer A is correct because the broadcast address is used to communicate with all hosts on the network. Answer B is incorrect because an ethernet address is not a type of IP address. Answer C is incorrect because the multicast type is used to communicate with a specific group of hosts on a network. Answer D is incorrect because the unicast type is used to communicate with a single host on a network.

Question 5	Answers C and D are correct. Variable length subnet masks (VLSM) and subnetting are two methods for splitting up a single network address into a number of smaller networks. Answer A is incorrect because fragmentation is used to split up ethernet frames when the amount of data to be transmitted is larger than the MTU. Answer B is incorrect because encapsulation is used in the TCP/IP model whereby each layer adds its own header information before passing the resulting packet on to the next layer. Answer E is incorrect because supernetting is the reverse of subnetting, where a number of smaller networks are combined into one larger network.

Question 6	The correct answer is D; the `in.mpathd` daemon is used to monitor multipath interfaces and to detect failures. Answer A is incorrect because `in.routed` is a routing daemon. Answer B is incorrect because `in.rdisc` is used to dynamically discover routers on the network. Answer C is incorrect because `inetd` is the daemon that manages network services and it does not affect multipathing.

Question 7	The correct answer is B. The file `/etc/inet/networks` is used to associate networks' names with network numbers. Answer A is incorrect because this file is used to specify network masks for the networks listed. Answer C is incorrect because this file provides the IP address to hostname mapping. Answer D is incorrect because this file provides the ethernet address-to-hostname mapping.

Question 8	The correct answer is D. Unicast addressing is used for one-to-one communication. Answer A is incorrect because this type of addressing is used to communicate with all nodes on a network. Answer B is incorrect because IP is not a type of address; it is a protocol. Answer C is incorrect because this type of addressing is used to communicate with a group of nodes on a network.

Question 9	The correct answer is D. The search order is determined by this entry in the `/etc/nsswitch.conf` file. In this case, `files` is the first entry, so the local `/etc` files are referenced initially. If this search is unsuccessful , the next entry in the list will be used, `nis` . The naming service `hosts` table is referenced and if unsuccessful, then the final entry, `dns` , is consulted. This will cause a `dns` search to be initiated. If the search is still unsuccessful, then an `unknown host` error message will be displayed. Answer A is incorrect because the entry would have to contain only the word `files` to search the local `/etc` files. Answer B is incorrect because the search order is from left to right and the entry would have been `dns nis files` . Answer C is incorrect because the entry would have been `nis files dns` .

Question 10	The correct answer is C. The correct method for calculating the Interface Identifier is to first convert the MAC address to binary. Next, toggle bit 7 and add the two octets (0xFF and 0xFE) between the CID and VID. Finally, convert the address back to hexadecimal. Answer A is incorrect because the conversion to binary is not included. Also, it is bit 7 that is toggled, not bit 8. Answer B is incorrect because the two inserted octets (0xFE and 0xFE) are wrong. The two inserted octets need to be 0xFF and 0xFE. Answer D is incorrect because it is bit 7 that is toggled, not bit 8.

Question 11	The correct answer is A. The Aggregatable Global Unicast address is used if you need to route an IPv6 address across the Internet. Answer B is wrong because this address type is intended for single, local network links. Answer C is wrong because this type of address is used by an IPv6 system to send datagrams to itself. Answer D is wrong because this type of address is used within an intranet.

Question 12	The correct answer is A. The custom JumpStart client uses RARP to identify itself by its ethernet address. The boot server looks up the ethernet address in its local `/etc/ethers` file to find out the IP address. Answer B is incorrect because ARP is used to map a 32-bit IP address to a 48-bit ethernet address. Answer C is incorrect because the IP protocol is not used at boot time for a system to determine its IP address. Answer D is incorrect because TCP is a transport protocol that is not used at boot time for a system to determine its IP address.

Question 13	The correct answer is C. The command `ifconfig hme0 inet6 plumb up` would correctly configure and enable IPv6 on the `hme0` interface. Answer A is incorrect because this would merely enable an existing IPv4 interface. Answer B is incorrect because the command syntax is invalid. Answer D is incorrect because the first argument to `ifconfig` should be the network interface, not the keyword `inet6` ”the syntax is invalid.

Question 14	The correct answer is B. The file `/etc/defaultrouter` is referenced at boot-time to add any static routes that have been defined. Answer A is incorrect because `/etc/inet/networks` is used to associate network numbers with network names. Answer C is incorrect because `/etc/rc2.d/S69inet` is a system startup script used to initialize networking processes. The file `/etc/defaultrouter` is referenced in this script to check whether the routing daemon should be started. Answer D is incorrect because `/etc/inet/hosts` is a file that is used to map IP addresses to hostnames.

Question 15	The correct answers are B and D because TCP and UDP are both Transport layer protocols. Answers A, C, and E are incorrect because they are Internet layer protocols.

Question 16	The correct answer is D. 1000BASE-T supports distances of up to 100 meters using CAT-5 cabling. Answer A is incorrect because 1000BASE-CX uses copper cable. Answers B and C are incorrect because these types use fiber optic cable.

Question 17	The correct answer is B because the record type `AAAA` denotes an IPv6 record. Answer A is incorrect because the type would be `A` . Answer C is incorrect because the type would be `SOA` . Answer D is incorrect because the type would be `CNAME` .

Question 18	The correct answer is A because the `xntpd` daemon sets and maintains the time of day, in agreement with Internet standard time-servers. Answer B is incorrect because `inetd` is the daemon that manages network services. Answer C is incorrect because `ntpq` is used to query NTP servers. Answer D is incorrect because `xntpdc` is used to query the NTP daemon.

Question 19	The correct answer is B. The file `/etc/hosts` is linked to `/etc/inet/hosts` and provides IP address to hostname mapping. Answer A is incorrect because this file is used to identify the network mask for the listed networks. Answer C is incorrect because this file maps network numbers to network names. Answer D is incorrect because this file determines the search order, depending on whether local files, a name service, or DNS is used.

Question 20	The correct answers are B and D. To change the IP address on the network interface `hme0` , you would need to edit the two files, `/etc/hostname.hme0` and `/etc/inet/hosts` . Answer A is incorrect because `/etc/inet/netmasks` is used to associate network masks with network numbers. Answer C is incorrect because `/etc/system` is used to set and modify system and kernel parameters. Answer E is incorrect because `/etc/nodename` contains the canonical name for the system. This file would be modified if you were manually changing a system's hostname.

Question 21	The correct answer is B. The command `/usr/lib/inet/dhcpd -i hme0 -d -v` would start the DHCP server daemon in debug mode with verbose output so that additional messages would be displayed. Answer A is incorrect because this command simply runs the daemon in normal mode. Answer C is incorrect because `dhcpconfig` is used to configure a DHCP server and the `-d` option is a sub-option used to define the DNS domain name. Answer D is incorrect because this command displays the status of an interface that is under DHCP control; it does not run the `dhcpd` daemon.

Question 22	The correct answer is A. The startup script `/etc/init.d/xntpd` is used to start the NTP daemon on an NTP client. Answers B and C are incorrect because they don't exist. Answer D is incorrect because this script is used to configure the network interface.

Question 23	The correct answer is A. Static routes are permanent entries in the route table. Answers B, C, and D are incorrect because they describe dynamic routing entries.

Question 24	The correct answer is B because TCP makes a connection prior to data transmission. TCP also utilizes acknowledgements as part of its provision of a guaranteed delivery mechanism. Answer A is incorrect because this describes a connectionless, unreliable protocol, such as UDP. Answer C is incorrect because TCP utilizes acknowledgements as part of its provision of a guaranteed delivery mechanism. Answer D is incorrect because TCP is connection oriented and establishes a connection prior to data transmission.

Question 25	The correct answer is B. The maximum amount of data that can be included in a single Ethernet II frame is 1500 bytes. Answer A is incorrect because this is the maximum length of an Ethernet II frame, including the data. Answer C is incorrect because this is the minimum length of an Ethernet II frame, including the minimum amount of data. Answer D is incorrect because this is the smallest value that the data field can be.

Question 26	The correct answer is D. The startup script `/etc/rcS.d/S30network.sh` automatically configures the IP address of the primary network interface. Answers A and B are incorrect because these are not system startup scripts. Answer C is incorrect because this script is executed at run level 2 ”the network interface is configured at run level S.

Question 27	The correct answer is B. The DNS name server daemon, `in.named` , starts only if the configuration file `/etc/named.conf` exists. Answer A is incorrect because `/etc/nsswitch.conf` contains information on lookups and the order in which data sources are searched. It does not affect the startup of the DNS name server daemon, `in.named` . Answers C and D are incorrect because these filenames do not exist.

Question 28	The correct answer is D. RIP is a distance-vector routing protocol that exchanges route information between IP routers within an autonomous system. Answers A and B are incorrect because they exchange routes between autonomous systems. Answer C is incorrect because OSPF is a link-state protocol that maintains a map of the network topology instead of working out route paths.

Question 29	The correct answer is D. The double colon (::) can appear only once in an IPv6 address.

Question 30	The correct answer is C. The command `boot net:dhcp - install` boots the JumpStart client to install using the DHCP protocol. Answer A is incorrect because this option would perform a normal JumpStart boot without invoking DHCP. Answer B is incorrect because this option performs just a network boot, such as that done by a diskless client ”again, without invoking DHCP. Answer D is incorrect because this option performs a DHCP boot, but does not invoke the JumpStart installation facility.

Question 31	A matches 3 because this device does forward packets based on the MAC Address. B matches 4 because a router forwards packets based on the IP Address. C matches 1 because a gateway connects networks running different protocols, unlike bridges and routers. D matches 2 because a repeater merely "repeats" the electrical signal. A repeater does not route signals to a number of ports, or specific ports; its function is to extend a network segment.

Question 32	The correct answer is B. The `-d` option to the `in.rarpd` command initiates the daemon in debug mode, providing additional messages. Answer A is incorrect because this option merely starts `in.rarpd` for all network interfaces. Answers C and D are incorrect because they are invalid arguments.

Question 33	The correct answer is B. The MTU value for a loopback interface is 8232 bytes. Answer A is incorrect because this is the MTU value for an ethernet interface. Answer C is incorrect because this value is the maximum size of an Ethernet II frame, including data. Answer D is incorrect because this is the minimum size of an Ethernet II frame, including the smallest data size that can be sent.

Question 34	The correct answer is B. A switch is the device that could reduce collisions by reducing the network traffic. A switch only forwards packets to the port containing the destination address. Answer A is incorrect because the hub forwards packets to all ports and does not reduce network traffic or collisions. Answer C is incorrect because this device connects networks together. Answer D is incorrect because the NIC is installed to enable a host to connect to a network.

Question 35	Answers A and D are correct, because IPv6 addresses can contain embedded IPv4 addresses and IPv6 addresses are 128 bits long, with octets separated by a colon character. Answer B is incorrect because this describes an IPv4 address. Answer C is incorrect because, although IPv6 addresses are 128 bits long, the octets are separated by a colon character. Answer E is incorrect because a system can have both IPv4 and IPv6 addresses ”it is called a dual stack.

Question 36	The correct answer is B. A classless address consists of the first 18 bits to identify the network and the remaining 14 bits to identify the host. Answer A is incorrect because this describes a class B IP address. Answer C is incorrect because this describes a class A IP address. Answer D is incorrect because this describes a class C IP address.

Question 37	The correct answer is C. The IP address `127.0.0.1` is used as a loopback address, enabling the host to send packets to itself. Answer A is incorrect because the hostname is assigned to the IP address of the primary network interface, not the loopback entry. Answer B is incorrect because the IP address `127.0.0.1` is a reserved address for loopback communication, not for the primary network interface. Answer D is incorrect because the loopback entry is not a test entry and it is used by the system to send packets to itself. It could be used, for example, where both the server and client portions of an application reside on the same physical host.

Question 38	The correct answer is B. A class B IP address contains network addresses where the first octet can be between 128 and 191 ”the IP address `146.100.20.5` falls within this range. Answer A is incorrect because this is the loopback address. Answer C is incorrect because this is a class C IP address. Answer D is incorrect because this is a class A IP address.

Question 39	The correct answer is C. The command `ifconfig hme0:1 plumb 192.168.5.8 up` will correctly configure and enable a logical interface on the primary network interface, `hme0` . Answer A is incorrect because the logical interface ( `hme0:1` ) is not specified ”the interface also needs to be configured using the `plumb` option. Answer B is incorrect because the logical interface needs to be configured using the `plumb` option. Answer D is incorrect because the IP address of the current primary interface should not be specified in addition to the logical interface IP address; the `plumb` option is also missing.

Question 40	The correct answer is B because NTP uses port 123. Answer A is incorrect because Telnet uses port 23. Answer C is incorrect because FTP uses port 21. Answer D is incorrect because SMTP uses port 25.

Question 41	The correct answer is D. The `HUP` signal causes the DNS daemon to reread its configuration file. Answer A is incorrect because this signal causes the DNS daemon to take a snapshot of its in-memory cached data. Answer B is incorrect because this signal turns off the debugging option. Answer C is incorrect because this signal increases the debug level by 1.

Question 42	The correct answer is `snoop` , because this command is used to capture packets on the network.

Question 43	The correct answer is B. Resolution is the term used to describe the smallest increment a clock can use. Answer A is incorrect because this describes precision . Answer C is incorrect because this describes accuracy . Answer D is incorrect because this describes reliability .

Question 44	The correct answer is A. The command `ifconfig hme0 dhcp` tries to obtain a lease manually. Answer B is incorrect because this would only disable and then enable the network interface. It would have no effect on DHCP. Answer C is incorrect because this would stop and start the DHCP server. Answer D is incorrect because this starts the normal process of automatically obtaining an IP address; it would not try to acquire a lease manually.

Question 45	The correct answer is B. The `/var/adm/messages` file contains error messages produced by the DNS server. Answers A, C, and D are incorrect because these files do not exist.

Question 46	The correct answer is A. TCP is a reliable, connection-oriented protocol and UDP is an unreliable, connectionless protocol. Answer B is incorrect because TCP is a reliable, connection-oriented protocol, not UDP. Also it is UDP that is unreliable and connectionless, not TCP. Answer C is incorrect because TCP is connection-oriented, not connectionless. Also UDP is not connection-oriented, it is connectionless. Answer D is incorrect because UDP is unreliable; TCP is the reliable protocol.

Question 47	The correct answer is C because you need to be root to see the ethernet address. Answers A, B, and D are incorrect because the IP address, network mask, and broadcast address are all displayed if you enter the `ifconfig -a` command as a non-root user .

Question 48	The correct answers are A and C. The JumpStart client must be of the ultra architecture ”that is, `sun4u` ”and must also have its boot PROM version at 3.25 or greater. Answer B is incorrect because the JumpStart server can be any architecture that is supported in Solaris 9. Answer D is incorrect because it is the JumpStart client that must have its boot PROM version at 3.25 or greater, not the server. Answer E is incorrect because the server and the client do not need to be on the same subnet. That is only necessary for JumpStart clients and boot servers when using the RARP protocol to boot; the DHCP protocol can boot across subnetworks.

Question 49	The correct answer is A. ARP is used to map a 32-bit IP address to a 48-bit ethernet address. Answers B and D are incorrect because they are invalid: IP addresses are 32 bits long and ethernet addresses are 48 bits long. Answer C is incorrect because this describes the function of the RARP protocol.

Question 50	The correct answers are B and C. Sun Trunking provides outbound load balancing when more than one destination is involved (there must be multiple destinations). It also allows up to two Quad Fast Ethernet cards (providing a maximum of eight network ports) to be combined to form a single "trunk" running at 800Mbps. Answer A is incorrect because this describes a logical network interface. Answers D and E are incorrect because these are not features of Sun Trunking.

Question 51	The correct answer is C. The command `ifconfig hme0:1 down unplumb` will successfully remove the logical interface `hme0:1` . Answer A is incorrect because the interface must be marked `down` before the `unplumb` option can be used to remove it. Answer B is incorrect because this only disables the network interface, it does not remove it. Answer D is incorrect because the interface has not been marked `down` . This needs to happen before the interface can be removed; otherwise , there is a risk that data might be lost.

Question 52	The correct answer is D. The `in.ripngd` is a routing daemon used in IPv6. Answer A is incorrect because this command is an IPv6 daemon used with autoconfiguration. Answer B is incorrect because the `in.mpathd` daemon monitors IPv6 multipath interfaces. Answer C is incorrect because `inetd` is the Internet services daemon and is not related to multipathing.

Question 53	The correct answer is B. The `netstat “r` command displays the routing table entries. Answer A is incorrect because this command displays the status of all installed network interfaces. Answer C is incorrect because this command displays network interface statistics. Answer D is incorrect because this command is used to inspect and modify network parameters. Answer E is incorrect because `print` is an invalid option to the `route` command in the Solaris operating environment.

Question 54	The correct answer is C. The Network Interface layer uses ethernet addresses as its basis for addressing. Answer A is incorrect because the Internet layer uses IP addresses as its basis for addressing. Answer B is incorrect because the Application layer uses application-to-application communications to address its peer. Answer D is incorrect because the Transport layer uses ports as its basis for addressing.

Question 55	The correct answers are A and B. The `dhcpconfig` utility is used to configure a DHCP server from the command line, whereas the `dhcpmgr` utility is used to configure a DHCP server in a graphical interface. Answer C is incorrect because `dhtadm` is used to manage configuration tables within DHCP and not to configure the DHCP server. Answer D is incorrect because `pntadm` is used to manage network tables within DHCP and not to configure the DHCP server.

Question 56	The correct answer is C. NTP servers advertise every 64 seconds on the network.

Question 57	The correct answer is C. Even though ARP has traditionally been listed as an Internet layer protocol, it actually operates between the Network Interface and Internet layers .

Question 58	The correct answer is D. The `USR2` signal is used to reset the debugging level to 0 ”that is, to turn off debugging. Answer A is incorrect because the `INT` signal is used to cause the DNS daemon to take a snapshot of its in-memory cached data. Answer B is incorrect because the `HUP` signal causes the DNS daemon to reread its configuration file. Answer C is incorrect because the `USR1` signal increases the debug level by 1 each time, providing more debug information to be displayed.

Question 59	The correct answer is C. Before assigning an IPv6 address to a network interface, the autoconfiguration utility checks to see whether the address is a duplicate. It does this by sending a solicitation message and checks for a response. If no response is received, then it is assumed that the address is unique and it is assigned to the interface; otherwise a message is issued and no further action is taken. Answer A is incorrect because addresses can be obtained by using a combination of both stateless and stateful autoconfiguration. Answer B is incorrect because manual intervention is required if a duplicate address is detected . Answer D is incorrect because stateful autoconfiguration is not the recommended method because it requires an additional means of providing hostname-to-IP address resolution.

Question 60	The correct answer is C. The window advertisement contains the number of additional bytes that can be sent. The window advertisement is part of the flow control available with TCP. Answers A, B, and D are incorrect because they are not contained within a window advertisement.

Question 61	The correct answer is `ndd` . This command is used to inspect and modify network parameters, such as the speed of the network interface. For a system with an hme network interface, the speed of the interface is viewed by entering the following command: `ndd /dev/hme link_speed` . A value of 0 indicates the interface is running at 10Mbps, whereas a value of 1 indicates the interface is running at 100Mbps.

Question 62	The correct answer is A. When a datagram is sent to an anycast address, only the nearest host that is a member of a multicast group receives the datagram. Answer B is incorrect because this type is used to communicate with all hosts on the network. Answer C is incorrect because this type is used to communicate with a specific group of hosts on the network. Answer D is incorrect because this type is used to communicate with a single host on the network.

Question 63	Answers B and C are correct. DHCP is used to automatically assign IP addresses to hosts. Using DHCP makes it much easier to renumber the network if the ISP changes. Answer A is incorrect because DHCP does not assign ethernet addresses; it assigns IP addresses. Answer D is incorrect because IP addresses assigned by DHCP are not static and can be changed easily.

Question 64	Answers A and C are correct. `SUNWfiles` and `SUNWbinfiles` are both valid locations for the datastore. The other valid option for the datastore (not shown in this question) is `SUNWnisplus` . Answers B, D, and E are not valid entries for the datastore location.