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DNS

Setup Settings DNS

ConnexCS provides a managed DNS (Domain Name System) platform geared towards VoIP delivery so low TTL's (Time to live) won't overload your DNS provider. We provide a white-labeled .sip.direct domain name which you can use directly or setup as a CNAME.

DNS on Day 1

When you setup your first customer or provider interconnect, you should try wherever possible to setup DNS. This means at any point in the future, if you deploy a new server, scale up/down, migrate towards or away, there will be little to no disruption to customer service.

DNS Setup

Set up DNS to load balance multiple Session Initiation Protocol (SIP) servers without a load-balancer.

  1. Click .

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  2. Enter the Domain for your company.

  3. The (TLD) Top Level Domain sip.direct is used to create the full URL.
  4. After saving, the CNAME information will eventually populate IP addresses.
  5. Check the records against the server IP.
  6. Select the distribution methods with "A Record' and 'SRV' tiers.
  7. Select Anycast Mirroring, if required.
  8. Click Save.

Example:

  • ABC Telco is the company, with domain abctelco.com
  • Set sip.abctelco.com CNAME to point to abctelco.sip.direct, with TTL of 3600 (seconds)
  • When a call comes in for sip.abctelco.com, it's forwarded to abctelco.sip.direct, and all calls for the next hour is forwarded to this address without doing the lookup

Distribution methods

  • A records: The A record (point a domain such as abc.com to 13.224.230.90) is the most common record in DNS. Select multiple A records to set a round-robin DNS query. This is the simplest form of load-balancing.
  • SRV records: Unlike A records, SRV records send (mirror) data for the SIP client. The SIP client can then make an informed decision about the servers to try and in what order. ConnexCS allows 3 tiers of Service records (SRV), though it's rare to use the Tertiary.

AnyEdge Mirroring

To make best use of DNS records, they should be aware of what is happening on servers which they serve. With AnyEdge Mirroring, the SRV Tier will match what is set by that AnyEdge setup. This means if there is any failure on the AnyEdge server, the DNS SRV record will correctly update to represent what config you have set on AnyEdge.

Perfect Redundancy - High Availability

There are many ways to achieve redundancy and mitigate any single-point-of-failure (SPOF). Here is the ConnexCS recommended setup for HA:

  1. Have more than 1 server on ConnexCS in different datacentres inside a cluster.
  2. Use ConnexCS AnyEdge system.
  3. Setup DNS records with a domain such as sip.mycompany.sip.direct (TTL = 60 seconds).
  4. Set ConnexCS DNS configuration to:
    • 'A Record' pointing to AnyEdge
    • 'SRV Primary' pointing to AnyEdge
    • 'SRV Secondary' set under AnyEdge Mirroring
    • 'SRV Tertiary' records as all or some of your servers manually set.
  5. Setup sip.yourdomain.com as a CNAME for sip.mycompany.sip.direct (TTL = 3600+)
  6. If you are deploying in multi-zones or larger deployments, you can segment things further as needed.
  7. On each server set 302 redirect to a counter server trying best to avoid any more SPOF, or hotspots.

This gives you the following advantages

  • You customer see's your brand on the endpoint.
  • You have the last word when it comes to where your traffic goes to, even if you move away from ConnexCS.
  • Your DNS provider doesn't have a high volume of traffic, so performance or dedicated performance isn't needed here.
  • TTL is 60 seconds on the records here, so they can be changed immediately if needed.
  • If your server reaches capacity a 302, redirect will help traffic failover to your other server.
  • Non-compatible SIP clients (no support for SRV records) will still be sending to AnyEdge which benefits by not having a Single Point Of Failure (SPOF).
  • If a server becomes unavailable, AnyEdge will detect this from a local zone and automatically mitigate it.
  • If a server becomes unavailable mid-call, AnyEdge will ensure that NAT hole-punching still works effectively for the registration, allowing calls to reach back to the network.
  • If AnyEdge becomes unavailable, DNS SRV records will direct traffic directly to the SIP servers bypassing the AnyEdge failure.
  • If there is any localized failure, traffic distribution will still be honoured as it's mirroring AnyEdge config.
  • For any AnyEdge config problems (human error) or AnyEdge failure, the last resort Tertiary will still get the call to a server.

Optional Domain Name per Customer

On larger deployments where you may want more control, it's possible to setup something such as yourcustomer.sip.yourcompany.sip.direct and even a CNAME for a vanity address. While this may be more work, it will allow you to shape your customers traffic distribution, perform A-B testing, etc.