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What is the difference between DDNS and DNS?
Difference between DNS and DDNS: • DNS is static which means it remains fixed for a particular domain whereas Dynamic DNS changes is dynamic in nature which means it changes every time. • Both the systems comprise of the TCP/IP protocol. • Both DNS and DDNS are developed because users cannot remember the numeric IP addresses of different websites.
What are the advantages and disadvantages of a CCTV camera?
The advantages of CCTV cameras are that they are kept everywhere. So if a crime is committed the culprit will be eventually caught.Disadvantages are that they are costly, do not always work(as they are not set up in the right places) and manipulate with people's privacy.Potential advantages.The advantages of CCTV cameras are that they are kept everywhere. So if a crime is committed the culprit will be eventually caught.One of the immediately obvious advantages is that the unit is no subject to the failure of any type of wiring. The cameras make use of wireless technology to accomplish the task at hand. This absence of wiring that could fail or be cut means there is much less chance of something going wrong with the unit, or that a clever thief can circumvent the system by severing the connection. Short of ripping the entire camera out of place, there is not much that will slow the unit down.Another advantage has to do with the clarity of the images that are captured. Most of these wireless units have a high-resolution image that makes it very easy to identify faces and other physical characteristics. This makes the cameras ideal for use as part of the security for research facilities and other establishments. Security personnel can easily monitor all activities within range of the cameras, and clearly note any suspicious or unauthorized behaviour, while getting a clear image of the person engaged in the activities.Recording is another advantage of these wireless cameras. In times past, storing recordings could be quite a task. From magnetic tape to VHS tapes, storage could become quite a problem. Many of the units on the market today make use of CDR technology, making it possible to store more hours of surveillance on a single disk. This can be crucial for law enforcement officials, as well as persons who are responsible for conducting security in office buildings and manufacturing facilities.Another advantage of these newer models of wireless surveillance units is that they are usually less expensive than most people would think. In fact, it is possible to purchase these types of cameras at a significantly less amount per unit than many of the wired counterparts on the market today. Coupled with the fact that wireless units make for much easier installation, it should come as no wonder that more and more people are choosing to go wireless for their security camera needs.Potential disadvantagesThe following are some of the potential weaknesses of IP cameras in comparison to other CCTV cameras.· Disadvantages are that they are costly, do not always work(as they are not set up in the right places) and manipulate with people's privacy.Higher initial cost per camera.[citation needed]Fewer choices of manufacturers.[citation needed]Lack of standards. Different IP cameras may encode video differently or use a different programming interface. This means a particular camera model should be deployed only with compatible IP video recording solutions.[citation needed]Technical barrier. Installation for IP camera required a series of complicated network setting including IP address, DDNS, router setting and port forwarding.[citation needed] This is very difficult for most users to do without help from an IT technician.Lower dynamic range - i.e. reduced ability to cope with low light and high contrast scenes.[citation needed]Vulnerable to hacking, and hoaxing via internet (numerous instances of false bomb threats being called in as hoaxers watch on web); criminals can hack into a facility's CCTV system to observe security measures and personnel, thereby facilitating criminal acts and proving the IP technology to be counterproductive
What is the function of resource records in DNS?
used by the server to resolve namesThe resource records are created to help dns work like zone ,ip to name vice versa. there are 23 types of resource record types defined for dns.DNS Record TypesA full list of DNS Record Types may be obtained from IANA DNS Parameters. RRValueRFCDescriptionhttp://wiki.answers.com/../a.HTML1http://wiki.answers.com/../apd/rfc1035.txtIPv4 Address record. An IPv4 address for a host.http://wiki.answers.com/../aaaa.HTML28http://wiki.answers.com/../apd/rfc3596.txtIPv6 Address record. An IPv6 address for a host. Current IETF recommendation for IPv6 forward-mapped zones.http://wiki.answers.com/../a6.HTML38http://wiki.answers.com/../apd/rfc2874.txtExperimental. Forward mapping of IPv6 addresses. An IP address for a host within the zone.AFSDB18http://wiki.answers.com/../apd/rfc1183.txtLocation of AFS servers. Experimental - special apps only.http://wiki.answers.com/../cname.HTML5http://wiki.answers.com/../apd/rfc1035.txtCanonical Name. An alias name for a host.http://wiki.answers.com/../dname.HTML39http://wiki.answers.com/../apd/rfc2672.txtExperimental. Delegation of reverse addresses (primarily IPv6).http://wiki.answers.com/../dnskey.HTML48http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. DNS public key RR.http://wiki.answers.com/../ds.HTML43http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Delegated Signer RR.http://wiki.answers.com/../hinfo.HTML13http://wiki.answers.com/../apd/rfc1035.txtHost Information - optional text data about a host.ISDN20http://wiki.answers.com/../apd/rfc1183.txtISDN address. Experimental = special applications only.http://wiki.answers.com/../key.HTML25http://wiki.answers.com/../apd/rfc2535.txtPublic key associated with a DNS name.LOC29http://wiki.answers.com/../apd/rfc1876.txtStores GPS data. Experimental - widely used.http://wiki.answers.com/../mx.HTML15http://wiki.answers.com/../apd/rfc1035.txtMail Exchanger. A preference value and the host name for a mail server/exchanger that will service this zone. RFC 974 defines valid names.http://wiki.answers.com/../naptr.HTML35http://wiki.answers.com/../apd/rfc3403.txtNaming Authority Pointer Record. Gross misnomer. General purpose definition of rule set to be used by applications e.g. VoIPhttp://wiki.answers.com/../ns.HTML2http://wiki.answers.com/../apd/rfc1035.txtName Server. Defines the authoritative name server(s) for the domain (defined by the SOA record) or the subdomain.http://wiki.answers.com/../nsec.HTML47http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Next Secure record. Ssed to provide proof of non-existence of a name.http://wiki.answers.com/../nxt.HTML30DNSSEC Next Domain record type. Obsolete use NSEC.http://wiki.answers.com/../ptr.HTML12http://wiki.answers.com/../apd/rfc1035.txtIP address (IPv4 or IPv6) to host. Used in http://wiki.answers.com/../ch3.RP17http://wiki.answers.com/../apd/rfc1183.txtInformation about responsible person. Experimental - special apps only.http://wiki.answers.com/../rrsig.HTML46http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Signed RRset.RT21http://wiki.answers.com/../apd/rfc1183.txtThrough-route binding. Experimental - special apps only.http://wiki.answers.com/../sig.HTML24http://wiki.answers.com/../apd/rfc2931.txt/http://apd/rfc2535.txtDNSSEC. Obsolete use RRSIG. SIG(0) is used as a special meta RR in DDNS and zone transfer security.http://wiki.answers.com/../soa.HTML6http://wiki.answers.com/../apd/rfc1035.txtStart of Authority. Defines the zone name, an e-mail contact and various time and refresh values applicable to the zone.http://wiki.answers.com/../ch9/spf.HTML99http://wiki.answers.com/../apd/rfc4408.txtSender Policy Framework (v1). Defines the servers which are authorized to send mail for a domain. Its primary function is to prevent identity theft by spammers.http://wiki.answers.com/../srv.HTML33http://wiki.answers.com/../apd/rfc2782.txtDefines services available in the zone, for example, ldap, http etc..http://wiki.answers.com/../txt.HTML16http://wiki.answers.com/../apd/rfc1035.txtText information associated with a name. The http://wiki.answers.com/../ch9/spf.HTMLand may (as of April 2006) be defined using an SPF RR. DKIM (http://wiki.answers.com/../apd/rfc4871.txtalso makes use of the TXT RR for authenticaing email. http://wiki.answers.com/../ch9/dkim.HTML.WKS11http://wiki.answers.com/../apd/rfc1035.txtWell Known Services. Deprecated in favour of http://wiki.answers.com/../srv.HTML.X2519http://wiki.answers.com/../apd/rfc1183.txtX.25 address. Experimental - special apps only.http://wiki.answers.com/../#directiveshttp://wiki.answers.com/../origin.HTMLhttp://wiki.answers.com/../include.HTMLhttp://wiki.answers.com/../apa/ttl.HTMLhttp://wiki.answers.com/../generate.HTML(non-standard BIND only)
What is the purpose of resource records in DNS?
The resource records are created to help dns work like zone ,ip to name vice versa. there are 23 types of resource record types defined for dns.DNS Record TypesA full list of DNS Record Types may be obtained from IANA DNS Parameters. RRValueRFCDescriptionhttp://wiki.answers.com/a.HTML1http://wiki.answers.com/../apd/rfc1035.txtIPv4 Address record. An IPv4 address for a host.http://wiki.answers.com/aaaa.HTML28http://wiki.answers.com/../apd/rfc3596.txtIPv6 Address record. An IPv6 address for a host. Current IETF recommendation for IPv6 forward-mapped zones.http://wiki.answers.com/a6.HTML38http://wiki.answers.com/../apd/rfc2874.txtExperimental. Forward mapping of IPv6 addresses. An IP address for a host within the zone.AFSDB18http://wiki.answers.com/../apd/rfc1183.txtLocation of AFS servers. Experimental - special apps only.http://wiki.answers.com/cname.HTML5http://wiki.answers.com/../apd/rfc1035.txtCanonical Name. An alias name for a host.http://wiki.answers.com/dname.HTML39http://wiki.answers.com/../apd/rfc2672.txtExperimental. Delegation of reverse addresses (primarily IPv6).http://wiki.answers.com/dnskey.HTML48http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. DNS public key RR.http://wiki.answers.com/ds.HTML43http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Delegated Signer RR.http://wiki.answers.com/hinfo.HTML13http://wiki.answers.com/../apd/rfc1035.txtHost Information - optional text data about a host.ISDN20http://wiki.answers.com/../apd/rfc1183.txtISDN address. Experimental = special applications only.http://wiki.answers.com/key.HTML25http://wiki.answers.com/../apd/rfc2535.txtPublic key associated with a DNS name.LOC29http://wiki.answers.com/../apd/rfc1876.txtStores GPS data. Experimental - widely used.http://wiki.answers.com/mx.HTML15http://wiki.answers.com/../apd/rfc1035.txtMail Exchanger. A preference value and the host name for a mail server/exchanger that will service this zone. RFC 974 defines valid names.http://wiki.answers.com/naptr.HTML35http://wiki.answers.com/../apd/rfc3403.txtNaming Authority Pointer Record. Gross misnomer. General purpose definition of rule set to be used by applications e.g. VoIPhttp://wiki.answers.com/ns.HTML2http://wiki.answers.com/../apd/rfc1035.txtName Server. Defines the authoritative name server(s) for the domain (defined by the SOA record) or the subdomain.http://wiki.answers.com/nsec.HTML47http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Next Secure record. Ssed to provide proof of non-existence of a name.http://wiki.answers.com/nxt.HTML30DNSSEC Next Domain record type. Obsolete use NSEC.http://wiki.answers.com/ptr.HTML12http://wiki.answers.com/../apd/rfc1035.txtIP address (IPv4 or IPv6) to host. Used in http://wiki.answers.com/../ch3.RP17http://wiki.answers.com/../apd/rfc1183.txtInformation about responsible person. Experimental - special apps only.http://wiki.answers.com/rrsig.HTML46http://wiki.answers.com/../apd/rfc4034.txtDNSSEC.bis. Signed RRset.RT21http://wiki.answers.com/../apd/rfc1183.txtThrough-route binding. Experimental - special apps only.http://wiki.answers.com/sig.HTML24http://wiki.answers.com/../apd/rfc2931.txt/http://wiki.answers.com/../apd/rfc2535.txtDNSSEC. Obsolete use RRSIG. SIG(0) is used as a special meta RR in DDNS and zone transfer security.http://wiki.answers.com/soa.HTML6http://wiki.answers.com/../apd/rfc1035.txtStart of Authority. Defines the zone name, an e-mail contact and various time and refresh values applicable to the zone.http://wiki.answers.com/../ch9/spf.HTML99http://wiki.answers.com/../apd/rfc4408.txtSender Policy Framework (v1). Defines the servers which are authorized to send mail for a domain. Its primary function is to prevent identity theft by spammers.http://wiki.answers.com/srv.HTML33http://wiki.answers.com/../apd/rfc2782.txtDefines services available in the zone, for example, ldap, http etc..http://wiki.answers.com/txt.HTML16http://wiki.answers.com/../apd/rfc1035.txtText information associated with a name. The http://wiki.answers.com/../ch9/spf.HTMLand may (as of April 2006) be defined using an SPF RR. DKIM (http://wiki.answers.com/../apd/rfc4871.txtalso makes use of the TXT RR for authenticaing email. http://wiki.answers.com/../ch9/dkim.HTML.WKS11http://wiki.answers.com/../apd/rfc1035.txtWell Known Services. Deprecated in favour of http://wiki.answers.com/srv.HTML.X2519http://wiki.answers.com/../apd/rfc1183.txtX.25 address. Experimental - special apps only.Answers.comhttp://wiki.answers.com/origin.HTMLhttp://wiki.answers.com/include.HTMLhttp://wiki.answers.com/../apa/ttl.HTMLhttp://wiki.answers.com/generate.HTML(non-standard BIND only)
