How does DNS affect VOIP Phones?: DNS ( Domain Name Server) generally used in computer language, it connect calls between VOIP users, enables DNS administrators to move services from one host to another and to use multiple servers. These records point to a specific SIP identity. Voice Over IP (VoIP) - VoIP service uses the Internet to make phones.
DNS play an important role  in running a network, and ensuring that devices such as VoIP phones work as they should. DNS correctly is important in getting the most out of your hosted PABX service. DNS is an important part of the web's infrastructure. No doubt essentially, it works as the internet's phone book.
How does DNS affect VOIP Phones
DNS and VOIP Phones
How does DNS affect VOIP Phones

Relation Between DNS and VOIP Phones


Every device connected to the network or the Internet, whether it is a web or email server or VoIP phone, is an IP address and DNS is used to keep track of all these addresses so that the devices can connect to each other. It lets your device to 'dial' to dial whatever device or service you want to connect with.

It is therefore obvious that it is important to ensure that all the devices in your network always get the latest IP address from the DNS server. If not, they can not communicate with us properly. It means without DNS server VOIP phone communication does not work properly.

This is a useful system because it allows network devices to increase capability or to make changes to respond to network problems. By updating domain name records, traffic can be directed elsewhere so that it enables the network to deal with outage or spikes in demand.

DNS is the one that allows the internet to respond to changes at any address. Once the IP address changes, the related domain name records should be updated just like updating a phone book when you move and any other server associated with it is also updated, so that they return all the current responses to all DNS lookups.

For example, instead of asking for a VoIP phone to access a converting hosted phone system, instead of asking to connect to a fixed IP address, the DNS lookup asks what the converting IP addresses are for that time.

DNS Services 


Not all DNS services play well with the rules and should not update the records regularly. The reason for this is that each domain name record has an expiration date, which is called "the time of stay" (TTL), which determines how often the server is valid and to get the latest address of the record For how often check is required.

The issue is that the ISP is sometimes dependent on the old values, so when a record changes, the information of the ISP gets outdated, and the end users will receive a response saying that they try to reach the address that is wrong.

Why do ISP do this? Well, they handle millions of DNS requests, so the number of records reaching their TTL increases rapidly, and taking care of all those changes is a drain on bandwidth and resources.

Therefore, we recommend that customers do not communicate with their ISP's DNS service, which will be programmed to use their router by default. Instead, we recommend that they use Google's public DNS resolution service. Whenever a record of a domain name is updated, we know that Google always knows about it.

The basic thing to understand when talking to the DNS is that if you want VoIP phone or any other network-connected device or service to work at all times, then you need to make sure the DNS lookup is returning accurate records.

In a specific voice network implementation, UC Client or SIP Phone is configured to request its local "recursive caching" DNS server. (This is called "recursive", because it makes several steps to come in the answer, and "caching" because it stores the resulting answers for some time.) This server is root and top-level domain (TLD ) Work with servers, handle domains like .com.Those TLD servers direct the recursive caching DNS of the DNS client to the official DNS server for the Voice / UC provider, and that the official server provides encryption settings for IP address, failure address, load balancing settings, and UC or Voice service.

Voice and UC operators who do not use the Internet. For cable operators, "Metropolitan Service Operators" (MSOs) and Fiber to Provides (FTTx) providers, DNS can be used, but this does not use root servers or TLDs. These operators can not provide their services on the Internet.

Operators who do not use DNS at all. Some networks are built with IP addresses configured so that the DNS is never used. As 2600 Hz argues, this strategy can mean that the renewal of the inevitable IP address becomes very expensive and can create an outage for customers."It can be dangerous if you have customers who provide your phone and later, you change data centers or IP blocks for some reason and there is no way to change the IP of those phones."

The most common mistake is that SIP phones and desktop UC customers are relying on local DNS servers in their data network. For some users, this is the old Windows server in the closet, but it is often the DNS software provided in the local router by the Internet Service Provider (ISP).

The risk is that when this is a malfunctioning of the local, weak or low-managed DNS server, the Voice / UC service fails. Voice / UC provider is responsible for important features such as the ability to operate emergency phone calls, or the ability to conduct business (video calling, desktop sharing, messaging, etc.), but all the services fail where local DNS The server fails.

Single organization to run the DNS server


Any single DNS server on the internet can be attacked and overloaded by using Botnet attacks. Even most organizations that offer DNS services can be overwhelmed. History shows that attacks are started against individual DNS operators. (Note that the Global Root DNS servers are under constant attack, and there are defenses that are effective till now.)

Each DNS record has a "Time to Live" (TTL) setting, which specifies how long the caching server should keep records.

Large value, such as 4 hours (which will be configured as 14400 seconds), has the advantage of being stable. If entry in the DNS system is interrupted, then make sure that the old records remain in the cache for some time. But the downside is that when the changes are required, the operator may have to wait up to four hours to go into effect.

The DNS registrar is responsible for loading the domain name information into the root and top-level domain (TLD) servers. For example, if you are the owner of VoIPCarrierX.com, you will pay a registrar like Register.com, GoDaddy, or EasyDNS to keep your data loaded in the root name server.

As discussed above, if a DNS registrar is attacked, then the attacker can control access to the domain name. But most top level domains (TLDs) are managed separately from each other, and it is worth noting that the whole top level domain can be attacked.