dns and name resolution

7/24/2019 DNS and Name Resolution

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DNS and Name

Resolution



• Computers communicate with each other using IPaddresses, whether IPv4 or IPv6.

• However, it’s difcult or most people to remember the

IP address or their avorite website or le server.• !he" li#e using riendl", te$t%based names.• !hus, naming s"stems are implemented to resolve the

riendl" names o computers with their assigned IP

addresses.• !he &omain 'ame ("stem )&'(*is the naming s"stem that +indows (erver - /servers use.

• 'ot onl" does &'( help users to easil" identi "devices, but man" other services such as 0ctive&irector" re1uire &'( so that clients and servers canlocate and communicate with domain controllers.



• Hostname !his is the ) riendl"* name o a computer.0ccording to &'( standards, it can beup to 55 characters in length. It is e1uivalent to acomputer’s rst name, or e$ample, C- .

•

Namespace !his is the name o a domain, notspeci call" an 0ctive &irector" domainthough. It’s a logical set o hosts signi ed b" a name

controlled b" a set o name servers. !his ise1uivalent to a computer’s last name7 the"’re all parto the same amil".

• 8or e$ample, 9ig rm.com is the namespace or hostsin the 9ig rm.com domain.

•

Fully Qualifed Domain Name !he 8:&' is thehostname appended to the domain’snamespace, such as C- .9ig rm.com.



• HOSTS File !his is a te$t le that staticall"maps hostnames to IP addresses.

• !his le is located inc;<windows<s"stem= <drivers<etc or standard+indows (erver - / installations and canbe used as an entr"%level alternative to a &'(server or name resolution in smallenvironments.

• Name Server !his is a &'( server that willresolve 8:&'s to IP addresses.

• 'ame servers also control namespaces orspeci ed domains. !he" will resolve re1uestsor that namespace rom &'( clientsthroughout the networ#.



• Hierarchical Naming Structure !he namespace is createdso that the le t part o a name is a subset o the right part othe name as shown in the 8:&'.

• +ith this, the naming servers can start at the right side o thename, and the responses rom the name servers will direct itto the correct naming server or a given namespace.

• c- . coast.9ig rm.com is the 8:&' or a server in thecoast.9ig rm.com domain.

• !his domain is actuall" a subset, or a subdomain , under thecontrol o the 9ig rm.com domain.

• >ou can sa" the same thing about 9ig rm.com or the .comtop%level domain name.

• !he strength is that "ou can as# the .com domain name

server where the 9ig rm.com name server is.• >ou can do the same or the coast.9ig rm.com server, andso on.

• !he 8:&' name directs the 1uer" to the right name serverthrough a process named recursion .



• Recursion !his is a server%directed process to resolvean 8:&'.

• I the server cannot resolve the 8:&' with its own

in ormation, it will send the 1uer" to other nameservers.

• !he recursion process comprises root servers anddomain name servers.

•

/oot servers are the top o the hierarchical namingstructure.

• !he root servers list the name servers that control thetop%level domain names such as .com, .gov, and .edu.

!he top%level domain servers control the registr" osubdomains beneath the top%level domain.• 8or e$ample, name servers or the mcse.com

subdomain are registered on the .com domain servers.



• Delegation !his means allowing another nameserver to control a subdomain o a givennamespace.

• 8or e$ample, the 9ig rm.com name servers candelegate control o the coast.9ig rm.com namespace to another server.

• Forwarding !his is an alternative to therecursion process. 8orwarding is a lateralre1uest toanother name server within the networ#. !heorwarding server obtains a response and rela"sit to the originating name server.



ones to !anage Namespaces• 0 zone is the database or a namespace. n the Internet,

there is a &'( server that controls the mcse.comnamespace. I "ou want the IP address or www.mcse.com,this &'( server will loo# in its @one )database* to nd theanswer.

• (o, "ou can create @ones on &'( servers to manage

namespaces.In +indows &'( servers, there are our t"pes o @ones;A (tandard primar"A (tandard secondar"A 0ctive &irector" integratedA (tub

!he stub @one doesn’t manage a namespace, however, andis more li#e a conditionalorwarder.



"rimary one !he standard primar" @one is a te$t le in which the servermaintains the records or a given namespace.Secondary one

!he standard secondary zone is the read%onl" cop" o the standardprimar" @one or an 0ctive &irector" integrated @one.

#ctive Directory $ntegrated ones !he &'( records are stored in the 0ctive &irector" database rather than

a te$t le.

!he @ones are replicated to all other 0ctive &irector" domain controllersin the domain rather than through the @one trans er process.

The stu% &one lists onl" the name server or a given namespace.

It holds no control over the @one, so it indicates onl" what server couldsupport name resolution or the namespace.



• Reverse 'oo(up ones• 0 forward lookup means the client provides a

ull" 1uali ed domain name and the &'(server returns an IP address.

• 0 reverse lookup does the opposite; theclient provides an IP address, and then the&'( server returns an 8:&'.



• Host and "ointer RecordsHost )0* and pointer )P!/* records are

the most common records "ou will ndin the orwardloo#up @ones and the reverse loo#up@ones, respectivel".

• !he 0 records list the hostname o thecomputer and return the IP address.

• !he P!/ records list the IP address andreturn an 8:&'.



• #lias Records0lias )C'02 * records are created to list asecondar" name or a computer. !his record

willlist the name and return the assignedcomputer’s 8:&'.

• !hese are use ul in the event o

replacing the server o a published name thatthe clients use to access applications orservices.



• !ail )*changer Records2ail e$changer )2B* records are or (2!P

communication.• 2ail servers re1uest 2B records to contact thereceiving (2!P server or that namespace.

!"picall", "ou will be setting these up in

an e$ternal &'( @one. However, the" ma" bere1uired internall" or speci c applications. !he2B record re1uires an 8:&' o the (2!P serverand a priorit" value.

!he priorit" helps determine which 2B recordto contact rst, and ne$t when more than oneare available. !he lower value wins out.



• Service Records• +ithout the (/? records, wor#stations and servers would not be

able to nd domain controllers. !he (/?records b" themselves involve onl" ve values;

•

Service Name !his is a standard value t"picall" preceded b" anunderscore, such as gc. or

ladp. !his is e1uivalent to a hostname and it would be tac#edonto the 8:&' o a service.

• Server FQDN !his is the server that provides the service.

• "ort !his is the !CP or D&P port on which the service is available. !he protocol is signi ed inthe registered name, such as !CP.

• "riority !his wor#s Eust li#e 2B recordsFit has a Gnumber%onepriorit".

• +eight !his is the tiebrea#er or priorit". eave it at - i "ou’re

not concerned with ties.



• Start o, #uthority Records0 (tart o 0uthorit" )( 0* record is a singlerecord within each @one. It has in ormation about

what &'( server controls this @one andparameters on how to treat the resolved records.

• It contains several values that shouldn’t bemodi ed b" editing the record.Name Server Records'ame server )'(* records list the servers thatcan respond to 1ueries or this @one. !here willbeat least one o these records in the @one.



/esources• www.intodns.com• www.m$toolbo$.com•

www.dnsstu3.com

http://www.intodns.com/

http://www.mxtoolbox.com/

http://www.dnsstuff.com/

http://www.dnsstuff.com/

http://www.mxtoolbox.com/

http://www.intodns.com/

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